Rob R

Also try reducing your support tip size a little as well, will make it a bit easier to remove without damage. R

Exposure on the Mars 2 pro for water washable grey resin ( for most elegoo resins actually) is 2.7. I have not had to deviate from that for the actual print exposure. For the initial base layers I have reduced the default exposure of 25 down to 12. It makes things easier to get off the plate and supposedly increases the life expectancy of the screen. But, exposure times are specific to printer models. Experiment time again. Rob

I always remove supports before curing. Fine and medium supports usually peel of like shelling prawns. If the support is on something delicate I will snip it with side cutters. You say you over exposed? Is that curing or printing? Curing I use short bursts (60 - 90 seconds) in a glass jar with tap water. Turning/repositioning between each burst to even out the uv exposure. You can tell when it's done by the "feel" of the resin. Better to slightly under than go over. I wouldn't say there are too many supports, possibly some may need repositioning, might be able to loose those going to the top of the cab backplate but generally you cant have too many. Keep going. You are getting there. From a wet weekend on Anglesey. Rob

That should look a lot better. Any remaining droopy bits can be targetted with an extra support or two for the next print and eventually it all comes good. Rob

Corner of tank next to firebox and a couple of bits of footplate near the front could do with a couple more supports. R

Fill in the gaps between your supports with lots of small supports, not so much to keep it stuck to the plate but to give something for the print to grow from. Hold it upside down and imagine the print growing like a crystal down from the plate. I find that supports make more difference than most of the other print settings, that and the angle to the build plate. Rob

That's looking very good Jim.

I'm glad you sorted the printing in the end. It really is a bit of a 'Black Art' but very satisfying when you wake up to a perfect print dripping from the build plate. Have the frames shrunk very much lengthwise? Being the (not very) longest part they should give you some idea of the shrinkage allowance required to fit your existing rods. A bit of experimentation will soon get you there. Onwards and upwards Rob

Jim beat me to it and quite rightly so, as the fact we have such a splended range of W irons is entirely due to him. Rob

I know someone who needs a couple of them........

Marc, Just noticed your reply. The axle hole is as printed (2mm) but when sliced the file was enlarged 3% to allow for shrinkage. Because I have put the full width boss on these wheels they go onto the axle nice and square (just winding them in by hand rather than a straight push at the moment). Getting everything nice and clean is important as the slightest bit of debris causes the rims to sit off true. Still experimenting at the moment, latest version has a substatial chamfer on the outside of the rim to reduce the chances of problems there. Rob

At the moment yes as that is all I am geared up for. They do seem strong enough - I have had to put little fillets in where the spokes join the boss and rim which has made a big difference. There is a bit of variation in the bore of the rims, 6 rims of which 4 are one size and the other 2 are both larger to differing degrees. If that is still the case on a production run then it is a simple matter of printing some centres with differing od's Black resin can be a bit problematical apparently due to differing exposure/curing times etc so I will back to the experimental stage until I can get the settings dialled in. Or just print them in grey and paint the centres before assembly which might be a better option all round. Rob

Version 4 mounted on an axle. Runs nice and true (pushed on by hand) except for one end that has an eccentric pinpoint. Black resin next to save painting inbetween the spokes.. Rob

Having a play with some 42" split spoke wheels. Just off the printer. I know I need to play with the shrinkage allowance but I am not sure if I need to "open" the spokes up a bit more. The prototypes I have been looking at are quite slender with very little gap between the spoke pairs. For some reason the raft has come out really thick. Something else to sort....... Rob

First post after the "break". Having a few minute spare at work tonight I have reworked the 42" 8 split spoke wheel, to refine it and to fit the SSMRS rim now that I have some to measure. v2 to the left, v1 to the right Printing tomorrow (later today when I get up that is).

Jim, I haven't got that far yet. My one and only attempt at printing direct to the plate (not a wheel) did not go too well. The print was ok, it just shattered trying to remove it from the plate. I have drawn these with a boss both sides as per the drawings I have so they wouldn't sit flat as they are. They look ok straight from the wash but I need to get some tyres before I can proceed much further. I think the spokes could do with thinning out as well. Back to the fence painting now Rob

Test print of the 42 inch 8 open spoke wheels on the printer as I type. Printing at 3 different angles to determine the optimum. The flat will print quicker, the upright will fit more onto the build plate. Hopefully they will all be round and true. When it comes to sorting out the bore for the axle I am going to try for a "firm sliding fit" (as opposed to a "light press fit") to make assembly easier and to prevent any chance of the boss from splitting. A drop of loctite should hold it all together as, unlike a loco wheel, once the back to back is set there is no need to dismantle the wheelset.

A recent visit to a fellow S Scale modeller has highlighted a requirement for a number of 3' 6" (or 3' 7") wagon wheels with 8 open spokes for a future project. There is nothing suitable in the 4mm ranges that can sensibly used so I thought I would have a go at printing some to suit the Society's 3'7" steel rim. First draft in TC It will need a bit of trial and error and quite a few test prints to get the od to suit the rim and the id to suit the axle allowing for shrinkage etc but that is the same with the loco driving wheels as well. Will keep you posted. Rob

At the recent SSMRS AGM in Burton Upon Trent I became the custodian of Trowland. I still haven't worked out how that happened, but it did, somehow. Trowland will be out and about in the future, just don't pin me down to a date just yet. Rob

New thin rim printed centre to the left, thick rim printed centre to the right, fitted into SSMRS steel rims. I will have to fettle the steel rims before final assembly, a little tickle with some fine emery on the front face is needed. The axle holes are round, I borrowed my sons fancy phone and the close up lens has distorted things a bit. Rob

It is surprising how much bigger the wheel looks with a thinner rim.

Timber, Thank you very much for the latest wheel .stl Printing as I type. Simon, yes the thinner rim is for the SSMRS tyres. The original was a bit chunky, especially for the 1850's locos I want to fit them to. Sample below fitted to a short test axle. Rob

Thanks Mike. I am currently using the Elegoo Water Washable Grey with the printer located in the spare bedroom/office. I can just about get away with it in terms of odour but anything smellier (ie a "normal" resin) is going to have to wait until the spring when I can reorganise shed and make it more workshoppy. Overall I haven't had any issues with the Water Washable, there are lots of reviews on interweb saying it cracks etc but I suspect that is down to part design (keep the cross section fairly uniform and no big thick lumps) and over curing. I usually cure in water (a jam jar full of "Corporation Pop" is enough for most things) on the Elegoo Mercury Wash and cure. First stage washing is in a 4 litre plastic container (ex baby bottle sterilizer) which gets put outside at regular intervals to cure the washed resin before disposal. I will keep playing for now, ultimately, if the wheels fail the tyres, axles and crank pins are all recyclable. Keep safe out there. Rob

One issue that doesn't help is the nuts on the axles I have are different diameters. I have parked that version for now and moving onto a plain hole through - for this case I don't need to quarter the wheel anyway so hopefully it is just a case of eventually landing on the right bore by trial and error. Here we have v3 with a 3.2 dia plain hole and a small chamfer at the rear to help the axle go in. On the printer soon. Rob

Timber, Ok, that sounds good. I still can't push the nut in on my first prints, probably due to shrinkage. The Shapeways prints of course use a differentmaterial and process so I will have to do a bit of trial and error. I have some printing now, set vertically on the print bed with the nut recess opened out to 3.3mm on the drawing. If this is too much then it will be back to the drawing board for a tweak or two. The push fit method will throw up a different set of issues, whether it is better or worse is just down to personal preference. In other scales I have had no issues with quartering, assuming the frame and coupling rod centres match and all the wheels have the same crank throw. I shall keep playing, Paul is sending some tyres so hopefully by the new year I will have some useable wheel sets. Rob