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Is there a method of adjustment to reduce the amount of 'backlash' in the vertical wheel that lowers the head?

Sandy

 

Edit - on the Proxxon mf 70!

Edited by Sandy Harper

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Is there a method of adjustment to reduce the amount of 'backlash' in the vertical wheel that lowers the head?

Sandy

 

Edit - on the Proxxon mf 70!

 

If all else fails you could rig a set of digital calipers (or even a set of analogue ones, or a proper DRO scale) to show the head position directly so you're not dependent on the handwheel scale to determine where you are vertically. It's an approach I've decided to adopt on my truly dreadful Chinese mill/drill, which has no reliable connection between handwheel and quill, apparently  :angry: .

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If all else fails you could rig a set of digital calipers (or even a set of analogue ones, or a proper DRO scale) to show the head position directly so you're not dependent on the handwheel scale to determine where you are vertically. It's an approach I've decided to adopt on my truly dreadful Chinese mill/drill, which has no reliable connection between handwheel and quill, apparently  :angry: .

That's a thought

Thanks

Sandy

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Is there a method of adjustment to reduce the amount of 'backlash' in the vertical wheel that lowers the head?

Sandy

 

Edit - on the Proxxon mf 70!

I think the backlash is due to end float on the screw, a bit of packing should reduce it.

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I no longer post on here regularly, since my posts accidentally generated some ill-feeling from one or two people.

However, having been gifted a machine tool part with no real idea as to how to use it, if at all, I thought I'd ask for advice.

Hope this doesn't bring out my haters again.

 

P1000051.JPG.6db0b87ea9a0057b9dc0cce367617a3e.JPG

 

P1000050.JPG.bcbce7a4b47a32ac3f09d6a72fc7597f.JPG

 

They guy that gave it me said it was a dividing head? It's for use with an Emco Compact 5 lathe, which I possess. I also have a milling machine by the same maker, with a co-ordinate table.

 

I've looked online but can't find any help as to how it's used. The ones I found had a side handle that rotated the disc and you had to rotate it so many times to do your milling, according to how many sides you wanted to mill?

 

The little handle that releases the holed disc is at the rear, making me think this wouldn't be much use bolted down flat, yet there are bolt holes there?

 

I've had it in bits, cleaned and oiled it and rebuilt it as you see.

 

Any help, or advice, gratefully received.

 

 

Edited by JeffP

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Hi

 

My dividing head can be rotated by hand with the chuck in place and has a spring loaded plunger on one side which drops into a toothed wheel providing the divisions. You then lock it in position using an Allen bolt.

 

Will this one turn by hand?

 

Cheers

 

Paul

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The bolt in the back fits into 4 different locations, giving you different dividing possibilities. So you have to pull the spring loaded bolt back, move the disc to the preferred location, and the bolt will go into the whole of this location.

After that you lock the rotating table so there is no play or no force on the bolt. But this should have been clearly described in the booklet you got with your EMCO compact 5 when you bought it. Don't you have the instruction book? 

I still have mine, even I have purchased the machine in 1982.... But: I have the German version...

 

Vecchio, proud owner of a compact 5 with almost all accessories...

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My lathe, milling machine and co-ordinate table came second-hand via a dealer, from the prison service, with an almost full set of ESX  25 collets thrown in, and a collet chuck for the milling machine. I now have one for the lathe too.

I MAY have some instructions somewhere.

What I couldn't get my head round was the difference between mine and the ones with a cranked handle that needed turning like five full turns plus 15 holes?

Why aren't they all as simple as mine appears to be?

 

Question to owners: is a new super-accurate three jaw chuck a worthwhile buy?

Mine has one with a closing mechanism like a drill chuck, although it is branded Emco.

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Another question.

 

After reading about a decent little jeweller's drill and a cheap Chinese co-ordinate table over at t'other place, I've invested.

 

The drill arrived and is very nice for the money. They go for over $100 in the USA. £47 here.

 

The co-ordinate table was described as needing "some work to get it to move freely and to get rid of any backlash"

 

Does anyone know how this is done? I can't post a pic as it hasn't arrived yet. But here is a link...I hope that is allowed:

https://www.ebay.co.uk/itm/6300-Mini-Precision-Multifunction-Worktable-X-Y-axis-Adjust-Coordinate-Table-GZ/143345255837?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649

 

 

I can't ask over there as I'm no longer a member. 'Nuff said.

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1 hour ago, JeffP said:

 

 

The co-ordinate table was described as needing "some work to get it to move freely and to get rid of any backlash"

 

Does anyone know how this is done? I can't post a pic as it hasn't arrived yet. But here is a link...I hope that is allowed:

https://www.ebay.co.uk/itm/6300-Mini-Precision-Multifunction-Worktable-X-Y-axis-Adjust-Coordinate-Table-GZ/143345255837?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649

 

 

These are a bit on the cheap and cheerful side, but are fine for some light work - I sometimes use one attached to a rivet press.  Some backlash is inevitable - if there were none at all you would find it very hard to turn the handwheels. If the table needs to be reversed for the next cut, machinists will always turn the handle back past the mark then advance it again to  take up any backlash.

 

If the backlash is excessive you may be able to adust the wheel on the shaft. If memory serves, the end thrust on these is taken up by the hand wheel bearing directly on the housing, which is not a particularly good feature. Packing it with steel washer is better, but you should still have a couple of divisions movement in the wheel before the backlash is taken up.  

 

Overall tightness may simply be a matter of the gibs needing adjustment. Back off the lock nuts and loosen the hex head grub screws a turn, then tighten as you would for any sort of machine slide. However with tools of this nature it often pays to take the whole thing apart and check for swarf and burrs on the ways and around the lead screws (this doesn't always happen in the factory -  there's a reason they are  cheap). A bit of hand finishing can make them capable of doing some decent light work as long as you accept their limitations. 

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2 hours ago, JeffP said:

 'Nuff said.

Would you care to elucidate, please?

 

David

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On 02/03/2019 at 12:05, JeffP said:

Question to owners: is a new super-accurate three jaw chuck a worthwhile buy?

Mine has one with a closing mechanism like a drill chuck, although it is branded Emco.

Sound like its a self centring 3 jaw chuck. If you put something round in it, say an endmill or silver steel and turn it by hand it shouldn't wobble. If you have a dial test indicator (DTI) you can check for run out. The issue with 3 jaw chucks is people tend to hold items at the ends of the jaws. This leads to them becoming bell mouthed and they only grip longer bar with the part of the jaws nearest the chuck. No matter how hard you do them up the work piece will wobble. More noticeable on smaller 3 jaw chucks as they aren't as strong and run out is more obvious due to the small size. Emco used to make the old Unimat lathes. You know its a Unimat as the bed was two 1/2" round bars. 

Edited by didcot
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1 hour ago, didcot said:

The issue with 3 jaw chucks ...

... is really that they are only nominally self-centring and are intended for holding round and hex stock more or less true so that you may machine the job from it.  If you need to turn the job around after you have parted it off and machine the 'back' concentrically with the 'front', then you need to set the job up in a 4-jaw chuck and clock it true, or hold the job in a collet.  It's not reasonable to expext a 3-jaw scroll chuck in any size to be as accurate at all diameters as a collet or an independant 4-jaw chuck (that has been trued 'by hand').

 

 

1 hour ago, didcot said:

You know its a Unimat as the bed was two 1/2" round bars. 

Well, the original Unimat SL had a bed like this but the much more common Unimat 3 and the Unimat 4 had a traditional cast bed:

 

image.png.05ee76683ddcec2fe35824fb3311d02e.png

 

David

Edited by Isambarduk
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6 hours ago, JeffP said:

Does anyone know how this is done? I can't post a pic as it hasn't arrived yet. But here is a link...I hope that is allowed:

https://www.ebay.co.uk/itm/6300-Mini-Precision-Multifunction-Worktable-X-Y-axis-Adjust-Coordinate-Table-GZ/143345255837?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649

 

 

Looks suspiciously like a copy of that fitted to the Proxxon MF70 Micro Milling Machine.....

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It seems pretty typical advice (including further back in this thread) that a small pillar drill is the best starting point for buying machine tools for modelling. But how far can you use a small mill to do the same things?

 

I followed the advice and bought a Proxxon TBM220 pillar drill at roughly the same time I was long-term loaned a Unimat 3 lathe. I'll be honest that I haven't spent as much time with either as I'd have hoped, but even then, I don't think I've actually made that much use of the drill compared to the lathe. The only things I've really used it for where its capabilities have been crucial have been drilling things like loco frame materials and spacers. In 2mm, those are pretty small and thin - nothing thicker than 8mm tufnol or 1mm brass, and the odd small brass tube.

 

But now I'm starting to think of things I'd like to do where milling would be the best way - solid frame spacers for loco chassis with cutouts for gears, etc. I'm a bit tight for bench space in my garage-workshop, so I'm wondering if I might actually replace the TBM220 drill with a Proxxon MF70 milling machine. Given how light-duty my drilling work seems to be, is there any reason why I shouldn't simply put drill bits in the MF70 mill and just use the vertical control when I want to drill a chassis frame hole, for example?

 

Justin

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1 hour ago, Isambarduk said:

  It's not reasonable to expext a 3-jaw scroll chuck in any size to be as accurate at all diameters as a collet or an independant 4-jaw chuck (that has been trued 'by hand'

Very true. A 4 jaw should also be used if you are only gripping a small amount of material at the end of the jaws. The extra jaw makes a difference.  This prevents your 3 jaw becoming bell mouthed as I was explaining. Black bar and castings should never be used in a 3 jaw. My apprentice  instructor would have had a fit if we tried that. The other consideration is the way the chuck is mounted. A good quality camlock/ taper nose mounted chuck is far more repeatable and accurate than one that simply screws on. The 3 jaw chuck on my Colchester Student is good to 2 thou, my collets are spot on. Collets are for light work only, so more suitable for modelling work.

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1 hour ago, justin1985 said:

It seems pretty typical advice (including further back in this thread) that a small pillar drill is the best starting point for buying machine tools for modelling. But how far can you use a small mill to do the same things?

 

I followed the advice and bought a Proxxon TBM220 pillar drill at roughly the same time I was long-term loaned a Unimat 3 lathe. I'll be honest that I haven't spent as much time with either as I'd have hoped, but even then, I don't think I've actually made that much use of the drill compared to the lathe. The only things I've really used it for where its capabilities have been crucial have been drilling things like loco frame materials and spacers. In 2mm, those are pretty small and thin - nothing thicker than 8mm tufnol or 1mm brass, and the odd small brass tube.

 

But now I'm starting to think of things I'd like to do where milling would be the best way - solid frame spacers for loco chassis with cutouts for gears, etc. I'm a bit tight for bench space in my garage-workshop, so I'm wondering if I might actually replace the TBM220 drill with a Proxxon MF70 milling machine. Given how light-duty my drilling work seems to be, is there any reason why I shouldn't simply put drill bits in the MF70 mill and just use the vertical control when I want to drill a chassis frame hole, for example?

 

Justin

 

Of course there is no lever on the MF70, which means that it doesn't emulate a drill press. The minimum spindle speed is 5krpm and that is way too fast for drilling imo. Peter Clark showed a method of holding frame material on an adaptation in the tail stock or slide (I can't recall whether it was one or both) of a lathe. That would be an alternative that would save bench space since you would need only the lathe. A book I've bought on his recommendation but not much read is milling operations in the lathe. I think it's by Tubal Cain, without going in the garage to look. 

 

I have an MF70, lathe, and a drill press (the latter is rather larger than I usually need) and am sure I could get by with one fewer of those tools so would be interested in other's answers to your question. I too have issues with space in my garage workshop.

Edited by richbrummitt
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1 hour ago, didcot said:

This is the Unimat I was talking about. Link here .

Yes exactly, the SL, which is one of the very early versions of the Unimat and it was/is not so common.  I was questioning your earlier statement  "You know its a Unimat as the bed was two 1/2" round bars." because most old Unimat lathes do not have two round bars for the bed, that's all.  David

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You can mill on a lathe with a vertical slide attachment. Myford were well know for the attachment. It's basically a vertical attachment with a slide that is wound up and down. It bolts on to the top slide of the lathe instead of the tool post. It then gives you x & y axis. You can mount a small vice or the job to it. The cut is applied by winding the job into an end mill or slot drill held in the 3 jaw or collet chuck. Think of the arrangement as a milling machine led on its back.

I suspect you could find something to adapt to most lathes. It's made easier if the top slide has tee slots for mounting. Accurate depth of cut can be tricky, you'd need a dti to measure the depth. But I made a small stationary engine using one.

 

Talking of drilling on a mill. It's much easier to drill on a mill, than mill on a drill. I would never recommend using a pillar drill as a mill. They aren't robust enough. The thing to remember is the Jacobs chuck on a pillar drill is most likely on a taper. One into the chuck and another into the spindle. Great for drilling, not for milling as the side forces can pop the chuck off the taper or cause it to drop out of the spindle. But it depends on the size or make of pillar drill. 

Dremels don't make good mills. Rigidity is the key in all machine tools regardless of size. You'd be surprised by the forces involved in taking even the smallest cut. The more cutting flutes on a small slot drill the better. 

A bit of a ramble but hope that helps.

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1 hour ago, didcot said:

The more cutting flutes on a small slot drill the better. 

Hmm, I'm not so sure about that. 

 

One of the advantages of a two-flute slot drill, particuarly whilst using small and not so rigid machines, is that whilst one flute is cutting the face of the slot the other is in fresh air doing nothing.  With a four-flute slot drill, for example, whilst one flute is cutting the slot there is a tendancy for the slot drill to be displaced to the side slightly so that the following flute takes a cut in the side of the slot and widens it - not so bad, perhaps, if it did it nice and uniformly and gave you an over wide slot but it rather doesn't do that and you'll likely finish up with a somewhat wavy slot.

 

Nearly all my slot drills are two-flute but my side and end mills are mostly four-flute.

 

David

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4 hours ago, didcot said:

You can mill on a lathe with a vertical slide attachment.

 

I bought one for my 9" lathes. Never found it to be much use - insufficient rigidity I think. Eventually I gave up and bought a gear-drive mill/drill. It's an ugly brute but it works well.

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The smaller 2 cutting faces/flutes do tend to deflect as you pointed out. I found that out to my cost on my cnc router. Having had a box of FC3 cutters left over from my Instrument Making days I used those instead. 3 cutting faces/flutes and a lot more stable. You can treat them like a slot drill as the cutting faces are off set, so don't produce a pip.The extra flutes make it less likely to deflect. Being tungsten carbide helps as well. In fact I would recommend Tungsten Carbide cutters for beginners. They can take a bit more punishment than High Speed Steel and are not much more expensive.

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Important thing is that the cutter is well centered. Then both faces will cut. So whenever possible use collets and not a drill chuck.

Also: Small machines like the unimat SL or unimat 3 are quite weak from mechanical point of view but also from motor power point of view. Tools which worked terrible on the emco work well now (found a Axminster (Sieg) SX2 with some superficial damage some years ago, was well worth the investment) 

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On 16/12/2019 at 18:59, justin1985 said:

<snip>

I followed the advice and bought a Proxxon TBM220 pillar drill at roughly the same time I was long-term loaned a Unimat 3 lathe. I'll be honest that I haven't spent as much time with either as I'd have hoped, but even then, I don't think I've actually made that much use of the drill compared to the lathe. The only things I've really used it for where its capabilities have been crucial have been drilling things like loco frame materials and spacers. In 2mm, those are pretty small and thin - nothing thicker than 8mm tufnol or 1mm brass, and the odd small brass tube.

 

But now I'm starting to think of things I'd like to do where milling would be the best way - solid frame spacers for loco chassis with cutouts for gears, etc. I'm a bit tight for bench space in my garage-workshop, so I'm wondering if I might actually replace the TBM220 drill with a Proxxon MF70 milling machine. Given how light-duty my drilling work seems to be, is there any reason why I shouldn't simply put drill bits in the MF70 mill and just use the vertical control when I want to drill a chassis frame hole, for example?

 

Justin

 

Another option would be to set up the Unimat 3 as a mill/drill press (assuming that you still have access to it), perhaps not as good or as versatile as the Proxxon but would take up less bench space.

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