4472 Flying Scotsman 5"

[tigerburnie]

More of an assembly really, all the turning was done for me in the kit, things like the boiler bands and handrails were not included in the kit and the brass chassis and bogies were made by me. I used to see them most days on the Great Central, along with B1's they were the last of the old LNER engines to run once the line was handed over to the Midland Region. I did have a white metal kit built B1 but sold that some years ago, the rest of my stock is ready to run these days.

[tigerburnie]

Possibly a Proscale kit, withdrawn with the rest of the range following a critical magazine review, IIRC. I built a Proscale Coal Tank, also over thirty years ago, the body was okay but the chassis design was hopeless and replaced with a set of AGW machined brass frames.

 

I still have the box it came in, but the label is damaged and I cannot read the manufacturers name on it, this had no chassis, I made that from scratch and fitted a Portescap motor.

[Jol Wilkinson]

I think Proscale kits came in long green boxes (suitable for storing a finished model) If yours had no chassis it may have not been in an original box. The only 4mm kit suppliers that didn't supply a chassis were those white metal kit manufacturers whose products were designed to fit RTR chassis.

 

Back to the OP, wonderful work.I have long fancied a live steam 3 1/2" or 5" LNWR loco of some sort (preferably a Teutonic, Jumbo or Cauliflower) but don't have the capability or facilities to build one, nor the time left to me to get started on a model engineering career. I shall have to content myself with building my 4mm collection of kits, although I do have an unbuilt Aster Gauge 1 kit in the to do pile.

[greenglade]

To finish off this week's progress I spent today looking at my (Baldrick's) cunning plan for painting the lining on the wheel axle center's. I turned up two dead ends, one to fit into the rotary table's chuck adaptor plate (there's a small spigot ) and the other from 1/2" BMS to fit into the drill chuck, I think you'll get the plan now even without the picture... Just in case it hasn't clicked yet this is a picture of the trailing axle sitting between the two center's.



A close up to show what I plan to do, next week (busy this weekend) I'll make up a bracket to hold the lining pen in place. This is my new 'Easyliner' pen which as can be seen is a bit tall to fit between the wheel and the chuck (head is at it's maximum height, so no room to play with there), my old Bob Moore pen fits much better being shorter. However, it then dawned on me that my collet chuck will give me more clearance as it's shorter so I will take a look at that on Monday. I need enough clearance so that I can secure the pen at an angle that won't foul the crankpins as the table is rotated, there's a bolt that's sitting in one of the table's 'T' slots which is engaged with the wheel spokes to ensure they keep turning. The current plan is to do all turning by hand, however, if I experience any problems when securing the pen via a bracket I could do this under power which may be easier to get a perfect line. The good thing is that these wheels were painted back in July so are fully hardened and easy to clean off any paint if not happy with the result.



The planned order of doing things, is the white lines first, let dry and then a black line inside of the white. I'll probably look at making some form of index on the bracket to keep all the same, the rest will be filled in by hand, still using the jig for an even spiral coat.

We'll see how things go next week...

Pete

 

[greenglade]

 

Post by greenglade on 2 minutes ago

This morning, as promised I made a start on the white lining, on the prototype this line is 1/2" in from the outer axle boss rim and 1/4" wide, or just over 1mm in and 0.5mm wide in 5" gauge. Last week it was pointed out to me by Mike (barlowworks) that I could use a 'bow' pen as the professionals do, to be honest, I had completely forgotten about this method even though I've used it myself in the past. This method is much faster and so I gave it a go today. First job was to 'hone' (file and sand down with fine W&D) the Bow tip as it's only a cheap pen that I had to hand, as it happens, I do recall talking on this subject in the past and being advised to get a vintage set of pens, this I had totally forgotten and will endeavor to find such a set in the near future.
Anyway, here's a picture of the (cheapo) pen and also a small plug that I turned up to fit into the axle centre points to keep the pen central.



Now, I need to leave the paint to dry a little before doing the black so I only have the white line to show for today, The line is currently a little thicker than it should be but it's only the first stage, I'll bring the black close to the white which should slightly overlap it and then fill the middle in which I'll probably do in the jig set on the mill last week. The last job will be to clean up any areas I'm not happy with, so far it looks reasonably good with little tidying required, we shall see if this is still the case once the white has dried and the black is applied. A picture to show that all wheels have had the white applied, there is no need to do the trailing axle as it's centre is hidden.



I now need to resist the temptation to get on and do the black... perhaps I'll see if I can find something else to do to distract me for a few days, I'm not brave enough to put the wheels in the oven set low for a few hours.....

More soon chaps and chapesses 

Pete

 

[Jol Wilkinson]

Pete,

. 

I wouldn't worry over much about the lining being slightly over scale. It will probably show up better when the loco has had some use.

 

It's wonderful to see you making such a great job of the paintwork. Many years ago I go to know Brian Badger who painted several 4mm LNWR carriages for me (before I learned how to create a reasonable result for myself). He was increasingly taking live steam painting commissions and was rather bemused that model engineers, who had invested so much time and skill in building superb model,s seemed to "give up" so readily when it came to painting the loco. Unlike the 4mm and 7mm modellers who were fairly price conscious, he thought that the model engineers weren't too bothered about the cost.

 

Jol

[greenglade]

Thanks Jol

 

I know what you mean, I often get comments like, 'don't worry about the paint not being perfect, I'll soon get damaged in use' 'or, 'the real thing isn't that good anyway'...that may be the case but for me it has to be as good as possible. When looking at a model the eye is always drawn to the bad bits, with bad paintwork catching the eye quicker than most bits.

 

I admire those who build and paint in 00, and produce such great looking models, I know only too well the strain on the old eyes this causes, I try to avoid the smaller scales these days, I have a number of O gauge models to build for myself one day, for that model railway if I ever get started.

 

As a professional model maker I always strive for perfection..never get there though...I don't think that such a thing is possible, good thing really as once you get there where's the challenge?..I keep trying though...

 

Cheers

 

Pete

[Grasshopper John]

Hello Pete, that looks the muts nuts Have a look at this thread re lining pens ect PAD (Peter) used to be very active on here but sadly for us he has stopped posting his brilliant builds, You could try a PM though he'svery knowledgable about pens ect.

 

http://www.westernthunder.co.uk/index.php?threads/drawing-instrument-restoration.7195/

 

ATB

John.

Edited January 22, 2019 by Grasshopper John

[greenglade]

Hi John

 

thanks for the link, I can't see it yet until an Admin authorises my application, I'll take a look one that's done...

 

many thanks

 

Pete

[greenglade]

I've now had a look John, not read it fully yet but some of those pen sets are lovely...must keep my eye's peeled for something...

 

regards

 

Pete

[mswjr]

Pete, I have lined some of my models in the past, I have used expensive and cheap,ish bow lining pens,I have had good and bad results with both, What i did learn from it ,is thst the tips have to be true to each other and must be smooth, An old draughtsman told me that he honed his every time he used it, So get a middle of the range one and experiment with it,You tube has some videos on how to do the tips, Hope this helps a little , As i bought a good one  (HAFF) and it was no better than the one i had, untill the tips were done.

[greenglade]

Thank's David, yes I did hone my pow pen before using it, this was something that was discussed at length on the MECH forum some years ago which is why I knew this had to be done. I will keep an eye open for a good vintage set, I won't be buying one for a while though as I have the boiler to pay for at some point in the next 18 months...

 

cheers

 

Pete

[greenglade]

Hi guys

Ok, so continuing progress with the wheels. I had mentioned (elsewhere) about trying a paint pen between centre's on the lathe for the next stage, I ditched that idea after it became obvious that I couldn't do this accurately with the crankpins fixed, so went back to the Bow pen. A wasted few days awaiting the paint pen delivery...lol

I have now painted the black, first using the pen and then filling in the middle with 2 coats by hand, not perfect yet but getting there, I shall leave this for a few days before using a fine brush to touch up and bit's that I'm not happy with. A picture just to show how things are looking so far.



I'll show this rather close up view of one of the wheels to give a better idea of where I am, as can be seen, the main problem with getting a solid 360 circle has been the keyways which are upsetting the smooth action of the pen. These are the main bit's that I need to touch in by hand once the black has had some time to harden.



With the painting put to one side for a few days I looked at some of those literally hundreds of little jobs that still need doing, in this case the dummy wedge adjusting bolts for the main axle boxes. Note to self here, next time do it sooner when there's more room to reach the parts, alas I don't have 11.3 scale hands...lol

This is the two side adjustment bolts with lock nuts on the sides of the horns, in this case, the crank axle horns. All main horns have these bolts.



Lastly, for today, the adjustment bolt/nut for the bottom of the wedge which goes through the horn stays, I haven't taken these into the horns themselves as that would be too much work for when needing to remove the stays. Instead, I have stopped the bolt as it touches the bottom of the horn, of course, this picture is taken upside down.




Tomorrow I'll find something else to do while waiting for 'paint to dry', one job still to do on the horns is to make/fit the oil unions for the oil piping to connect too, I'll probably take a look at that once the wheels are refitted and the chassis is the right way up again. 

More soon.

Pete


 

[greenglade]

Hi guys

I've been taking care of a few bits that need doing before I can refit the wheels, hopefully for the last time? I first touched in a few areas of the lining that was bugging me, I may revisit some parts when I'm not going cross-eyed, they will do for now.

I next needed to take care of the 1/16 taper pin in the trailing wheel and have taken a few pictures to show how I did this. I first needed a way of reaching the crankpin to drill the hole, no.57 in this case. Due to the size of the wheel I had to use a pin vice held in the chuck, I also had to revert to my older chuck which is shorter then the nice new one even though it has worn jaws, after a little play I got the drill to run true. The first picture shows the basic set-up to give some idea of how I tackled this job, it's only a test at this stage, I had a few things to check before drilling, including lining up with the hole which clearly hasn't been done in this picture.

 

Once happy with how to hold the wheel using two pieces of wood in the machine vice and with the other wheel blocked to support it's weight, I then checked that it was indeed square in both plains. here I am using a large square to check that the axle is horizontal on the 'Y' axis. Of course, the machine vice has already been clocked to be in line with 'X' axis

 

The crank pin was placed to be upright by eye, the crank pin cap needed to have it's flats horizontal, this is critical or the drill will both miss the hole already drilled on the other flat and not be central in the thread, hope that makes sense?

And this closeup shows that I got things right, for both sides too, happy days. Mind you, by God are close up's cruel? these parts look rough and yet are very smooth to the eye and touch...

 

With the No.57 now drilled right through it was time to create the taper, there was no way that I could do this on the mill as Steve had kindly pointed out that the large end needs to be closest to the axle to stop the pin being forced out by centrifugal force, thank's for the heads-up SteveP, I hadn't considered this simple fact. So I had to do it by hand holding the 1/16 taper reamer in a pin vice. The picture shows that job completed, the wheel was laid on it's side with tissue under it for protection and also across the top for the same. As can be seen, I haven't gone too deep with the reamer as I want to keep the pin as close to scale as possible, IE: the further you go, the larger the pin.

Here's the pin tapped in place, I'll cut this to length later and also remove the green paint from the pin.

 

The last picture for today to show all axles refitted except for the crank. Also of note is that the main springs have now been painted. One thing that i had forgotten until refitting the springs is that I haven't made the special bolts yet that secure the spring buckle to the axlebox swivel, I can do this later as nothing needs to be removed to do this.

 

So, before I can fit the crank axle I need to finish the squaring of the crank pins, make the return cranks and the jig to fit them. I haven't digested the principle to all this yet so may be asking some questions along the way to clarify things, let's see how the old brain works first...

thanks for looking in guys.


Pete

Read more: http://modeleng.proboards.com/thread/5733/building-don-youngs-doncaster?page=134#ixzz5eIEvOjgr

Edited February 1, 2019 by greenglade

[greenglade]

I had a lot of problems trying to upload this post with images embedded, I used to be able to just copy and post from the other forum I give updates on, hope the issue here gets sorted as it took me a lot longer to do this manually..

 

Pete

[greenglade]

Good day, all..

Return Crank:

This will take at least 2 sessions, perhaps 3 as I'll try to cover all stages which although not that long in workshop time, it does take a while to edit pictures and write out. 

First up to show what's actually being made, this is Don's drawing which more or less follows full size, in fact, the only thing that may be different is the width of the slot which looks a little wider. There is a 'half' error on the drawing, the front face is correct but the side shows a much shorter shallop, you can see where I have corrected thi in pen so that hopefully I won't forget when machining this 1/32 scallop on the front face, the rear scallop is fine. As you can see I often scribble notes on these, in fact this drawing now has much more notes but not worth taking another picture for. Oh before anyone eagle-eyed points out that half of 7/32 is not 0.120, yes I know it's 0.109, I'm just giving myself a little more meat for when profiling the side profile curve...



I didn't have anything close to size to machine this so have had to use some 8mm flat gauge plate, BTW I plan to do all of the motion in either HROP steel as the coupling rods have been so done and gauge plate, the returns cranks are the first parts in gauge plate.

A large enough section for two return cranks was reduced to 7/32 as seen here.




I then marked out the area with a marker pen for the first crank blank to be cut using a slitting saw, this was cut 1/16 oversize for both blanks to be machined square together in the next stage. With the first cut completed, I then blocked the plate up for the second blank to be cut out.



here is the final cut in squaring up the two blanks, the cranks at their widest are 0.6875, I have machined them to 0.7000, again to give some meat for machining the 11/32 radius around the square hole later.



I then temporarily glued the two blanks together and machined one end face ready for the more critical session, ie drilling the holes.



Next was to set a 'stop' for which I used a large 'G' clamp and positioned the two blanks upright ready for drilling the bolt and taper pin holes. The end face was clocked , both blank centres where clocked and checked against rough marks done beforehand, just me have a visual point or line to refer too. The first hole was centre drilled 0.120 from the end face and zeroed on the clock. This first hole was drilled using a N0. 34 and I then moved along the 'X' axis 0.4376 to tackle the smaller No. 51 drill, this will be taper reamed later once fitted to the crank pin. Next job was to move along the 'Y' axis 0.2187 to find the middle of the other blank and repeat the process but in reverse starting with the N0. 51, it was just quicker that way. Picture shows all 4 holes completed...



It was then on to the two holes that define the crank on the other axis, With the blanks turned on their side and positioned back against the stop and with the head still at the N0.34 position all I had to do was move along 'X' by 0.2187 to find the centre of the square and drill out the 7mm hole. I did this slowly in steps as 7mm brings the hole very close to the square edges and didn't want any form of deflection from trying to drill the hole in one go, all drills were sharpened first. Once happy with the first hole I again moved along 'X' this time by the required 1.441 for the second hole, this one is 3/16 reamed. This will be threaded to 7/32 x 40 later, I first need to use it to plot the throw of the crank and also to machine the radius around it.



Next job while the blanks still had square facings was to cut the slot through the 7mm hole, I first used and slitting saw with a 1mm blade to go through the first section while held in the machine vice and then carefully cut the next part after the hole was a hacksaw in the vice using the machined slot as a guide. You will note that i have scribed a line for where the slot stops.



And here is where we are tonight, I have scribed out roughly the crank profile as a visual guide for once I start machining. I will turn up a 7mm mandrel to hold the large end of the crank in the rotary table for the first stage, hopefully, tomorrow. You can see that I've stuck the 3/16 reamer through the smaller hole to keep everything aligned as I'll profile the blanks together, just as I have done all of the drillings, it's just how I like doing things when matching pairs are involved.




thank's for looking in, this one has involved a little more typing than normal, glad I didn't try to do it all in one session..

cheers

Pete

EDIT:

I forgot to add that after the slots where cut I then ground down a small flat file to open them up to the 3/64 as per drawing, the bottom of the slots are completed but I still have a little more to go on the first part to match. The ground down file used can be seen in the last photo, I also ground off both side edges to stop the slot inadvertently getting any longer. 



Read more: http://modeleng.proboards.com/thread/5733/building-don-youngs-doncaster?page=134#ixzz5em9NMcAi

[greenglade]

Hi guys

 

I'm sorry but this site is still not working as it once was, I have left the link to my build for those who wish to see the pictures. If/when this site reverts back to how it was I will try to add the missing pictures, I just can't do it manually each time, It took me 2 hours to do the other two sites I give updates too, I just can't spend another half hour or so doing it here too, guess I'm just getting too old.....Before the recent issues, all I had to do was copy and paste from Mech to here and it worked with all the pictures included?

 

hope things revert back to normal soon...

 

Kind regards

 

Pete

[mswjr]

No pictures showing on here at my end Pete, I have seen them on M,E,C,H. thou, i dont comment on that as i do not log in, just read whats new, Nice work.

[greenglade]

Yes, it's a shame ...it was so simple to do before...I may try to go through it manully when I can...

 

Pete

[Mike Boucher]

11 minutes ago, greenglade said:

Yes, it's a shame ...it was so simple to do before...I may try to go through it manully when I can...

 

Pete

I've found that the new software is a LOT easier to attach photos that then old.  Drag the files from your PC/mac folder right into the create post section, set the mouse where you want a photo, and click the + in the appropriate photo.  You can drag all the files in one operation.

Before, it was click a button, find the file (one at a time), then it would show the path, and you had to click another button to upload the file to the forum, and then you had to click a 3rd button to insert the photo.

As for your C clamp stop, I'm not sure I follow why you needed the stop there.

BTW - Now I've found yet another model engineering forum to follow.  Ugh, too many forums to read!  (RMweb, modelenginemaker, homemodelenginemachinst, and now the model engineering clearing house...  )

[greenglade]

Hi Mike

 

The problem for me is that I write the master update on the mech forum which takes time, I then go to my face book page, upload the pictures and copy/paste each bit of text for each picture. This all takes time, hours and doibg it for a third time may be a bit much to ask...I will try, tonight I'm just a little tired. Before the issue on RMweb all I had to do was copy the entire entry from the Mech forum and paste it here...this I did tonight but it no longer includes the pictures. For the previous update I did it all manually as you describe but it's frustrating after being so easy  before.

 

Regarding the stop, it's there to give me a register so that when I finished the holes on one face, I could simply turn the work on it's side and know exactly where the first holes were in relation to those about to be drilled as they needed to be precise to each other..hope that makes sense.

 

Cheers

 

Pete

[Mike Boucher]

4 hours ago, greenglade said:

Hi Mike

 

Regarding the stop, it's there to give me a register so that when I finished the holes on one face, I could simply turn the work on it's side and know exactly where the first holes were in relation to those about to be drilled as they needed to be precise to each other..hope that makes sense.

 

Pete

That makes sense.  I only use stops when I'm making multiple pieces and i'm switching pieces in and out of the vise.  Whenever I re-orient a single piece, I use the edge finder (on the same edge as initially if at all possible)

[greenglade]

Day 2 on the Return cranks:

Apologies for the quality of the first picture, I've posted it as I explain what I have done prior to any machining of the crank profiles. The picture shows the mandrel for the larger end, this is 8mm bar stock, stepped down to 7mm to fit the large hole and then down to 6mm, finally tapped M6, the nut is just a 6mm nyloc that I had. I also made a similar 3/16 mandrel for the smaller hole. I then machined 2 buttons, one at 11/16 and the other at 13/32 for machining the two rad's, these were parted at a width that ensured the nuts would tighten down fully on the crank blanks.

 

next up was how to hold the blanks for machining? the first thing I did was find some sacrificial alloy plate to mount on, I think this was 8mm but didn't measure it, it's not that important. The first job was to centre the rotary table, I did this quickly using a length of steel that I machined to fit the chuck arbour pivot hole, held in the mill chuck and centred the two. Once this was done and with the arbour removed I placed the alloy plate near central on the rotary table, used a square of the column to keep it parallel to 'Y' axis as I like to keep things square with a number of datums to use/fall back on as a reference.

 

With the alloy clamped tight to the rotary table, I first drilled the 8mm hole, moved along 'Y' 1.441 and drilled the smaller 3/16 hole, this now gave me a starting point for the various machining operations ahead. The picture hopefully, shows the setup, oh and before I forget, I moved 'Y' back to it's zero for the first job of machining the 9/16 tongue and then the larger of the two rads. Hope you guys are keeping up with my ramblings...

 

 

This picture shows the tongue machined to width and the first side of the 11/16 rad roughed out, the ridge that can be seen in this picture between tongue and rad was removed on the final pass. Just to explain the flat section on the button and a couple of nicks in it. The flat section is just what's left of a keyway, the mandrel was made using a test piece of EN8 used when machining the keyways for the crank axle. The nicks were me checking there was no run out from the table before making a start, I got a bit heavy handed..

 

With both sides of the larger rad arcs done (both sides) I then tackled the taper to the smaller rad. Again I used a square off the column to line up with the scribed taper lines on the blank, I couldn't quite get the square to the line due to the smaller button so eyeballed it as close as possible. Once happy that the line was as close to parallel to 'Y's as I could tell, I began machining in steps, as I got close to the line I could see that it was a fraction out and adjusted accordingly, in fact it was only half a degree so not bad for 'eyeballing'.

 

The last picture for tonight shows the other side also completed, once I had done both tapers I then did the final cuts to the tongue on both sides to blend everything in. Of course before doing the other side I first needed to move the clamps to give clearance. Note that a 3rd clamp has been added, this was to keep everything secure as I undid the other two clamps and changed them over, as the 3rd clamp wasn't in the way I left it in situ. Oh, you may notice the photo album in the background with close-ups of 4472's return crank, over the last 20 years I have amassed hundreds if not thousands of photo's and drawings for this locomotive and it's class. I use them all...

 

 

Tomorrow (all being well) I'll repeat the set-up process but this time setting the 3/16 hole central for the machining of the smaller rad. I will then separate the two cranks, check that the taper looks central and reset for machining the front and back faces. The same alloy plate will be used to hold each crank for machining. Since the crank is square to the plate this should be relatively simple in the machine vice. I will modify the two mandrels to have a thread on both sides for holding each crank to the plate for this process, if I'd been thinking clearer I'd have done this in the first place and wouldn't have needed a clamp to hold the blanks down?... oh well, we all live and learn, mind you I'd have still used a clamp, I wouldn't want to trust everything to a tightened 'nut'.., like me....

More soon


Pete


Read more: http://modeleng.proboards.com/thread/5733/building-don-youngs-doncaster?page=135#ixzz5esWVwtHw

[greenglade]

Hi Guys


Well this will take more than the 3 sessions as I originally thought but the bulk of the work is now completed, I'll finish them next week.

So for today, we have the completion of any machining required, first up was to machine the smaller radius. The picture shows the setup ready for machining, this went smoothly without any mishaps. As can be seen, I first hacksawed off the excess material.

 

Here are the two cranks now separated and given a cleanup to remove any Loctite residue. No polishing yet as I still have a lot of metal to remove.

 

I then took a look at the rounding off of the tongue, I decided to do this by hand, using a suitable flat file while held in the vice with soft jaws. The picture shows the first stage of roughing out.

 

Next job was to file to shape using some slightly oversize washers held with an 8BA CSK bolt, the picture shows this stage. I will finish this off in the final polishing to be done once all machining is finished.

 

Next, I tackled the front face, the front is done first as it's just removing a middle section leaving an equally spaced piece of metal for when machining the back. The rear scallop removes all of the metal from the same position as the front all the way down including the smaller radius which would mean the job needing blocking out, not a good way of doing things, IMHO of course. I have put guidelines in to give me a visual of the area to be removed.

 

And here's the first front face finished, all I had to do now was remove the crank and fit the next as the position is dictated by the jig, I zeroed the end nearest the larger radius and made a note of the reading for the other end, the depth of the cut is 1/32 or 0.031 thou.

 

And the rear face, I took a small risk here, well let's just say not recommended practice. I first machined the area the same as the front at 0.030 deep, switched off and removed the small mandrel, fitted it the other way around so that he still located the crank. and then using my thumb to apply a little pressure I continued with the cut at the same depth of 0.030 thou, I then returned the cutter to the other end, set at 0.031 and did one continuous cut. I was confident of things not moving as the mandrel stubs were a good fit, I was confident with the setup and it worked but not something that I would recommend...

 

A cruel closeup, don't you just hate wide lens camera's... So, here we see both front and back views together, when I get to the final filing/polishing I'll remove all of the machine marks but probably only from the front face, life's short enough as it is... Oh, best mention that the reason the left-hand rear face smaller rad doesn't look symmetrical, it's ok, puzzled me too, to begin with until I realised that I hadn't removed the burr after machining, that poor 6mm cutter is pretty blunt now...

 

The last picture showing the two cranks face to face, I'm pleased with how they are coming along, there's a little smoothing out to do still, as mentioned they will get a final file/polishing session to complete, I'll do the square hole first.

 

That's it for this week, the plan for next week will be to machine the square ends on the crankpins, finish the opening of the slots and file the square holes to fit cranks to pins. Then, drill the No.51 hole through the crank pin and taper ream it for a suitable taper pin. I then need to make a scribing jig similar to that used full size to set the crank throw and hopefully by the end of the week have the return cranks fitted as per drawing. We can but hope...

Cheers

Pete

[greenglade]

Post by greenglade on 6 minutes ago

Tonight's update isn't the last for the return cranks but I'm nearly done so it looks like it will be 4 sessions in all.

Today's job was to turn the round hole into a square scenario, I first turned up an offcut piece of 12 mm BMS round bar, reduced a part of it to 7mm (just enough to be held securely in a chuck) to fit the hole already drilled in the return crank. I checked for runout on the rotary table which was about 2 thou, not great but good enough for this particular exercise. The first picture shows the turned part being held in the rotary table's chuck ready for machining the square.

 

Here's the plug finished, there's two reason's for making this gauge, first is to get the desired size for the square, the quill was left locked at the finish height ready to machine the crank pins themselves. The other reason is to be able to mark out the position of the square, more about that later.

 

With the first crankpin fitted in place of the plug, it was a simple job to machine the square, I did this in gentle steps not wanting to risk anything at this stage. If the crankpin had a centre hole on this end face it would have been prudent to do this between centres but there is no such hole on the prototype so I just took it slowly. Since the finished height was already set, all of the force was against the chuck rather than down on the crankpin so it was safe to do it this way even with the overhang.

 

Finally, the crankpins are finished as seen here and the plug has been put into one of the return crank holes to check for size.

 

And here's the second reason for the plug, with the crank face marked out in pen and the plug, lined up using a rule across it's two points of the horizontal square by eye I held it tight with a tool clamp and marked out the square with a scribe ready for a session with a file or two.

 

The filing took a lot less time than I expected, there wasn't really that much metal to remove, the scribed square was just touching the sides of the hole which made things much quicker. The picture shows the first crank fitted to its pin, well nearly fitted, it's still a little tight even with the taper pin to open the square but it's very close.

 

Lastly, a view of both crankpins with their return cranks partially fitted, as can be seen, the taper pins have been removed. They may be a tad too tight still as they require the taper pin inserted to help remove but then I think the prototype may be the same so will leave them 'as is' for now.

 

Hopefully, tomorrow I should be able to finish this part. I need to drill through the No. 51 hole, fit a taper pin, make up the securing bolts and also make up a jig for setting the throw, all being well I should find time to do all this tomorrow, oh and an awful lot of finishing/polishing the surface....famous last words but here's hoping...

Cheers

Pete

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