Member postings for Julius Henry Marx

Hello:

Sory for the delay in my reply.

I see.

Yes, I have noticed that there is some play at the left end of the leadscrew.

Makes sense. But when I was testing/adjusting the new gibs with the Bellville washers without the leadscrew in place, I observed that the was some tightness at each end of the run.

Yes. The Sieg C0 has a leadcrew nut that is adjustable in height, apparently to deal with that problem.

Good job that one. I'm still attempting to figure out how to get that done on mine.

Thanks for your input.

Best,

JHM

Edited By Julius Henry Marx on 26/07/2023 23:05:51

Hello:

An update:

After a fortnight or so I had to dismantle the carrier again to take some measurements and had a look at the new brass gibs. I then realised that they needed a tad more removal from the surface they are bolted on to, so went about doing that.

It was not a case of line wearing as the width of the markings on the brass were quite consistent with the markings I had measured on the OEM lift strips but as the use of the set screws was needed, I decided to go ahead and see what I could do.

It was a very small amount and the result was quite satisfactory, to the extent on not needing any adjustment from the Sieg C0 type set screws I had added.

But then I found out that the whole arrangement had become more difficult tighten, I guess due to the smaller dimensions at play and the 0.7 pitch of the mounting screws.

The solution (again) was to follow Kiwi Bloke's advise and use Bellville washers, so I added a pair arranged in series (on top of the OEM washer) to each screw.

The carrier now moves very smoothly and, as expected, gets tighter as it reaches each end of the bed.

I expect that, as the gibs wear the carrier will loosen up and then it will become necessary to use the set screws to adjust the gibs accordingly but I think it will take many hour's use of the U3 for that to happen.

Here's a photo of the gib below the flat as seen from the tailstock end, with the Bellville washers clearly visible:

It looks like it is as Kiwi Bloke said: She'll be right.
That's about it for now.

Best,

JHM

Edited By Julius Henry Marx on 23/07/2023 16:37:43

Hello:

Given your knowledge and experience in these matters, I cannot but accept your point of view as the most valid one.

Of course, there is no other way. 8^)

Thank you very much for taking the time to write it up, much appreciated.

Best,

JHM

Edited By Julius Henry Marx on 01/07/2023 13:47:28

Hello:

I'm sure you know more about the timeline than I, so I stand corrected. Thanks for clearing it up for me.

Yes, I have seen their web page. I was not able to get a reply from them when I emailed asking about a feedscrew nut for the U3's saddle, so I made one from SAE68 bronze.

I'll check on that when I take it apart again.

All that does is speak (very) highly of your knowledge and expertise as a tool maker, knowledge and expertise which allowed you to use a U3 for your professional work in spite of its shortcomings.

It also speaks of your degree of professionalism as a contractor. ie: you did not supply a good enough part, you supplied what for you was a perfect part. One with your name and reputation behind it.

That said, I think that wanting to know about the material used by Emco to manufacture the U3's carriage leadscrew may be slowly but steadily moving into what could possibly constitute contentious territory.

My opinions on the U3 are from a newly arrived retired professional (from another field of work) with no prior knowledge of what it was about. I only speak (with or without reason) of what I discovered after purchasing it.

So I will pause this thread now and come back (or start another) once I receive the new leadscrew and draw up/turn a new right hand bushing that I can test and report on.

In the meanwhile, I still have other U3 things to work out and will continue to seek advice here at ME.

Once again, thank you (all) very much for your input.

Best,

JHM

Hello:

No idea. Like I have previously mentioned, never seen one, only looked at the diagrams and mentioned that they were a few modifications.

I really cannot say. The store deos sell Sieg lathes/mills and most every part for what they sell. I will have to wait till it arrives and compare it to the OEM one.

Thank you very much for your input.

Best,

JHM

Hello:

I am quite sure of that, as sure as that at one point the accountants were given a say in the matter. Probably marking the moment when elegance in enginering morphed into compromise.

In my limited design experience (architect) with various materials, my opinion is that it definitely would.

I seriously doubt that they would have used Mazak.

One thing I have learnt is that reducing costs while at the same time compromising basics is not a good choice.

In have an undated *.pdf file containing part of a larger catalogue from a company called Blue Ridge Machinery and Tools, in the US offering a basic Unimat 3 (U3, driving plate, lathe dog, 2x dead centers, tool holder, service tools and instructions) for US$345.00. Adding steady rest/3-jaw chuck/six tooks and live center made it a US$499.00 deal and a further addition of vertical head/milling table/drill chuck and a set of drilling tools made it a US$725.00 deal.

Just to get an idea, in April 1980, you could get a hot dog+small Coke in downtown Manhattan for US$1.00 and these days just the hot dog goes for no less that US$5.00 and a small coke ~US$3.00.

As I see it, the problem is that well enough and perfect are highly subjective concepts. In my field of works it always makes for a permanent discussion topic with clients and developers.

Thank you very much for your input.

Best,

JHM

Hello:

I beg to differ. If what I have read on the web is correct, my Unimat 3 was manufactured in 07/1980, 43 years ago this month. Apparently it was discontinued in 1990, which (if accurate) would make it 10+ years without modification, at least from Emco.

From what I have seen in exploded parts diagrammes, Sieg made quite a few modifications to what they manufactured based on the original Emco design, never seen one save in photos so I cannot speak of quality.

That said, I have seen a great many U3 modifications published/shown on the web and I am sure there are many more that have not been published.

I believe that (one of) the most interesting ones is Maurice Rhode's, followed by your take on the feedscrew nut and tailstock modifications.

Both Kiwi Bloke and you agree that it would be the best solution, so that what I will attempt to do.

Yes, I expect there is, as always.

Thnaks, I'll have to keep an eye on that then.

Yes, it could well happen. But I don't think there's a way to get a brand new OEM part these days and for the US$36 this Sieg part cost me, I thought it was worth seeing what I could get from this manufacturer.

Better that than risking my pension money on a perfect state, very little use, no returns accepted etc. sample from the usual suspects on flea bay.

And then, there's also the present state of the thread on the leadscrew post to take into account.

I had some idea but only when I purchased my U3 did I realise just how exponentially expensive precision can be. Having experienced the results of U3 Emco manufacturing of the U3, I can only say that I have serious doubts with respect to what tolerances Emco may have used viv-a-vis the ones used by Sieg in their C0 version of the U3.

Thank you very much for your input.

Best,

JHM

Hello:

Yes, I also use grease but the careful adjustment of the hand wheel/acorn locknut was not possible till I made the modification to the handwheel. For the time being it works smoothly, much better that before.

Could be. I have come to think that overkill is usually (not always) highly dependent on the end result.

eg: while drawing up the Unimat 3, someone at Emco thought that manufacturing the carriage in the same material as the bed was overkill, that an adjustable tailstock was overkill and that having a replaceable leadscrew nut made from a suitable material was also overkill.

And here we are. 

I agree. I make sure there is no tightness and that the feedscrew turns freely.

Thank you for your input.

Best,

JHM

Edited By Julius Henry Marx on 29/06/2023 21:09:35

Hello:

Yes, I agree. It is very easy to fall into that hole.

Does not seem to be bronze so it could well be cast iron. Thanks for that bit.

Not really, just want it to work as well as possible. The thrust washers will probably do well enough.

Thank you very much for your input.

Best,

JHM

Hello:

Quite so, even less. Making a bad design worse.

Which is why I will have to think about a different, probably more complex design for the feedscrew / new bushing arrangement.

Thank you for your input.

Best,

JHM

Hello:

Indeed, I misunderstood / misread by me.  8^°

The OEM arrangement for that function (thrust bearing) uses part of the surface of the leadscrew end against the left side of the steel bushing: (sorry for the untidy sketch)

ie: steel against steel.

Indeed ... Food for thought.

I will have to change the design for the part to be screwed on to the right end of the new leadscrew I ordered and also new bushing. I have a whole 60 days to think about it.

Right, now I get it.

Yes, that and a smooth turning surface for the handwheel to land on.

Thank you both for your input, much appreciated.

Best,

JHM

Edited By Julius Henry Marx on 28/06/2023 19:09:40

Hello:

Of course ... 8^)

Right threads end | -> bushing with flange | -> flat thrust bearing | -> handwheel  <<- leadscrew inserted from here

^^^ This whole arrangement, if properly assembled, can be removed/replaced buy just loosening the set screw at the right hand side and unscrewing the last few cm.

Than you for your input.

Best,

JHM

Edited By Julius Henry Marx on 28/06/2023 13:11:52

Hello:

Indeed ... | Been there, seen that, suffered handwheels in other tools/equipment.

Yes, which is why the flange I am planning to add to the new bushing will have to have a thrust bearing before the new handwheel which would also provide the smooth running hard steel shim washer you mention.

The thing will be to source the right size bearing with a 6mm bore.

Thank you for your input.

Best,

JHM

Edited By Julius Henry Marx on 28/06/2023 13:12:29

Hello:

Well ... If it were only the U3 ... 8^)

For the time being I am doing (surprisingly) well with the washers, handwheel surgery, etc. so that is not a huge problem at the moment, but I don't want this hack to be a perma-temporary thing.

So I have sent for a replacement feed screw from a vendor of all things Sieg at Aliexpress. If the photos are anything to go by, it looks like it is much better made than the one from my U3:

The main reasons for having sent for a new one (aside from the original one being 43 years old and in awful shape) being the ready-made availability and the real life difficulty of getting a shop to make a bespoke one for me, much more being just one and not two dozen.

My plan is to make a part with the same diameter as the left end of the leadscrew (6mm) and a full length concentric hole with a M5x0.8 thread, obviously with a non-threaded part for it to fit properly.

This part will most probably be made out of hard bronze and be threaded into/ locked with a suitable (soft) anaerobic to the right end of the screw. The length this part will be defined when I decide how to fix a new handwheel and/or some attachment. eg: a toothed pulley to drive the feedscrew FF / FR using a small 12V motor.

The right end of the feedscrew, now having a longer ⌀ 6mm end with a male M5x0.8 hole will run inside a new, longer steel bushing with a flange on its right side, maybe with a small recess to hold a small thrust bearing if I can find a suitable one.

I thought for some time of doing that same thing before fixing (?) the lift strip problem, but concluded that it was not something to do without risking making things worse.

Thank you very much for your input.

Best,

JHM

Hello:

Yes. But the 5mm threads in my U3's leadscrew were damaged when I purchased it. There was no way I could adjust that properly.

Thanks for your input.

Best,

JHM

Hello:

Yes. But the handwheel was already in very bad shape so I really did not mind shaving a part off. I was woeking on a bushing and got the best of me.

For the time being (till the leadscrew gets fixed and a new handwheel gets made) it works surprisingly well.

Thanks for your input.

Best,

JHM

Hello:

Of course. But if/when doing that the part I will fit will be the same diameter as the left end ie: 600) and work in tandem with a new, longer bushing with a flange where the inner surface of a new, different handwheel will land on.

Than you for your input.

Best,

JHM

Hello:

All your posts have been quite helpful.

Yes, I agree it is/may be minimally loaded. But then, why did the OEM turn it down to ⌀ 5mm? Emco would have left it at the same diameter as the left hand end and used a screw to fit the handwheel in place.

Quite so. But as both the threaded section of the leadscrew and the right steel bearing are shorter than they should be, there is no proper axial constraint. Hence the washer at the left hand of the leadscrew and the need to add small washers at the right end to keep the handwheel from seizing.

Given my situation (ie: right hand M5 damage) the washer solved the axial movement I had which, combined with the backlash, was very annoying.

Indeed ...

Provided it is the right length so as to be able to make any necessary adjustments and at the same time provide a surface for the inner face of the handwheel to land on. That was not possible for me without the left hand washer, mainly because of the M5 damage.

Yes, I have been thinking about that quite a bit lately. But I'd need another working lathe or a spare leadscrew to do the job on my U3.

That's what I may end up doing, it will alow me to make all the modifications I need.

Thank you very much for your input.

Best,

JHM

Hello:

Yes, that I was aware of.

Makes sense. ie: your deduction, certainly not the use of Mazak for a non-replaceable carriage lead screw.

Quite so, just like the rest of the power train arrangement.

Incredible that the right end of the lead screw gets reduced to ⌀ 5mm before going into the steel bushing to then be threaded to M5x0.8 for the handwheel. Someone was not thinking right ...

I purchased some Chinese made ones some time ago but will have to make some other modifications to be able to use them as they are.

I think that the leadscrew should be properly supported at the right end, ie: in the same way it is at the left end, ⌀ 6.0 mm inside a steel/bronze bushing.

To that effect, whatever system is used to secure the handwheel should be implemented from the steel bushing/bronze onwards, ie: towards the right. This would mean a new, different bushing design and handwheel arrangement.

Thank you for your input.

Best,

JHM

Hello:

The OEM carriage feed screw on my Unimat 3 one came with damaged threads at the end of the M5 section, where the handwheel is fixed.

I managed to solve that problem (temporarily) by doing away with enough of the cylindrical part of the handwheel so that the nut that fixes in place would thread in properly, losing the ability to have an idea of how much I was advancing the carriage.

The other very annoying problem it came with was that the edge of the plastic with the numbers/divisions rubbed against the end of the bed.

This because, instead of a uniform flat surface at right angles to the bed, it has a roughly finished curved one. 8^°

Putting a light bevel on the plastic and adding a polished brass washer made a world of difference.

So, aside from a new handwheel, I am going to need a new carriage feed screw.

The options I have seen are:

1. a used one on the web. (not really)
2. a new one made by Sieg for the discontinued Sieg C0
3. a new one made locally (if I can find someone to do it)

The last option would solve a third problem I ran into when I first disassembled the machine: the length of the threaded section of the OEM carriage lead screw is actually shorter than needed by a few millimeters, requiring a 6mm x 8mm brass washer of the right thickness at the left end to fix it.

I have checked the length of the thread in the available Sieg part and they are the same as the one I have. ie: 302mm

I don't have the specification for the steel used in the OEM part so as to see about having one made or if maybe some other more suitable steel could/should be used.

I'd appreciate comments on this.

Thanks in advance.

JHM