X2 Mini Mill backlash, and parts supply etc

[Jim BaxterParticipant @jimbaxter34386]

Hi – I've just joined up the forum after having my machines (Sieg X2 and Sieg C3) for about 7 years but never properly learning to set them up and use them with any methodology greater than semi educated (if that) guessing!!

For some reason I suddenly had the notion a week or so back that I should take the time to learn some of the basics I never made the effort to do from the outset so I'm looking at things like alignment of my machines etc.

So I've meddled with my lathe a bit and got it working a bit more smoothly (had already fitted better brass gibs, a DRO set, and taper bearings to it some time ago). I measured runout on the spindle, and tonight I tried my first ever thread cut with a pleasing result too.

But I want to improve my mill a bit as the backlash in the table x & y axis is horrific!!

Planning on stripping the table down to see if I can reduce this anywhere with adjustments or shims etc, but have not yet found a good guide on this. Am I being really dumb or is it not such an easy thing on my mill as on the lathe somehow?

I've got a belt drive conversion en route and I can't wait to install that.

Aside from backlash, the next thing I want to do with the X2 is to fit the air spring conversion as the head on my mill drops when near the top and it's annoying. So I was going to order the kit from LMS but the postage is pretty bad. More over, they sell little upgrade kits with 'self locking' set screws for the lathe/mill and better axis lock handles etc. These kits are cheap and look like they could be beneficial but again, even if I buy them without the air spring kit the postage bumps up cheap parts to quite a bit more.

So question re' parts is can I get those sort of grub/set screws in the UK anywhere to fit my machines? And what is it that makes them self locking anyway? Would like to get these minor bits & pieces if they will help refine my machines even just a little, but not if I've got to pay loads for getting them here.

Not seen these bits on Arc or Chronos, but wondering if anywhere else in the UK might have this sort of stuff, or goodies in general for sieg machines like these?

Appreciate if anyone has useful info re' the above anyway, and am looking forward to learning more on here in due course.

Cheers

Jim

[Jim BaxterParticipant @jimbaxter34386]

[Russell EberhardtParticipant @russelleberhardt48058]

Hi Jim,

There is an article on Arc's site here on rebuilding the X1 mill. The table is basically the same as yours so that should help.

The backlash can be caused by two things; end float on the leadscrew which is adjustable or play in the nut which is split and can be tightened with a grub screw. If you want to reduce backlash further you can fit thrust bearings to the leadscrew and replace the leadscrew nut with an adjustable Delrin one. I have only one or two thou backlash after doing that see this thread on another forum shows how I did it.

Hope that helps,

Russell.

[Jim BaxterParticipant @jimbaxter34386]

Many thanks for the useful reply Russell

I took the table apart last night and was kind of surprised that there is no support for either of the x/y lead screws at the opposite end for the handle, and that other than the brass nut (which obviously moves from one end to the other) there is no support really at all. Even the bearing/bushing at the handle end is wobbly, which I wasn't expecting!

I will definitely have a look at those links, thanks – they sound like a great starting point. Does anyone tend to add parts at the far end of the lead screws to support them at all? Or is there no real need for this?

Thanks!

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Jim Baxter on 30/10/2013 22:56:53:

So question re' parts is can I get those sort of grub/set screws in the UK anywhere to fit my machines? And what is it that makes them self locking anyway?

.

Jim,

I can't speak for those particular parts, but there are a couple of ways that screws are made self-locking.

1. A small Nylon [or similar] insert, embedded in the thread
2. A patch of special Loctite which is dry, but liquifies under pressure.

MichaelG.

[John HinkleyParticipant @johnhinkley26699]

Although my mill isn't an X2, it had the same sort of "features" as yours. I solved the backlash problem by fitting DROs to all three axes. I went for the "cheap" end of the market, just to dip my toe in the water and I must say, I have been delighted with the result. You can forget about backlash completely. Best money I've spent so far in the workshop ( and I've spent quite a bit – just ask my wife!) you can see some photos of the installation in my albums, should you wish. I have every intention of re-doing the mounts for the scales, so that they'll be the "right way up", someday, but I was so keen to get them up and running, I took the easy way out and haven't got around to sorting it, yet.

Good luck, whichever path you choose to tread.

John

[John ShepherdParticipant @johnshepherd38883]

Jim

If you want to save some money on the air spring conversion have a look at the following :**LINK**

[Michael GilliganParticipant @michaelgilligan61133]

Jim,

As mentioned earlier

Here is an example

MichaelG.

[Jim BaxterParticipant @jimbaxter34386]

Thanks for all the input today chaps – really appreciate the info.

Will look into seeing if I can get one of those bonnet struts John. I'll try to get the same thing or for a similar size car at least since it could be easy to buy a random one and have it too strong/not enough etc.

I've never heard of that loctite as described – sounds weird so I'll look that up, thanks Michael. I like the idea of the pin insert type grub screws so I will see if I can obtain some of them in the uk.

Annoyingly it seems that the table arrangement on my X2 is not like that of the X1 alas. On my machine the lead screws have a brass screw nut that is not split, and cannot be tightened in that respect.

The brass nut on the X/Y is not bolted to anything, but rather sits in a slot in the table castings, and has a grub screw to push against it to an extent. Not sure if this is much use but I shall clean it all up, oil it, and reassemble taking that into account, and see if I can get anywhere with meddling with it. Currently I get about 8-10 thou backlash on the table!!

Russell – how is the end float adjust on the lead screws? Sorry if I'm missing the obvious! Is that via your addition of the thrust washers? Like the idea of that but I wouldn't be confident at this stage of doing a good job trying to machine out the housings to accommodate them.

The delrin screw nuts are a good idea so I'm wondering if I can do something similar with mine.

Interestingly, the opposite end of the lead screw to the handle has a large slot machined in it for something (on the X axis anyway, but not Y), yet there are not parts anywhere near it. As mentioned, the lead screw is all over the shop on the X as it is held in place by the hand wheel and bushing/bearing at that end, and slightly by the brass lead screw nut, which itself is not really held as such. So support for the screw opposite the handle end is non existent basically.

I'd love to add a bracket & bearing of some sort as I bet it would make it smoother and easier to adjust where I can, but not sure how feasible that is.

John – LOVE the thought of fitting DRO kit to it, and was looking at roughly what it might cost minimum to do that last night, but it looks like around £300-400 to do that and there's just no way I can do that any time soon as I've no budget really at the minute and have been spending on other stuff recently. I think I'd be divorced if I did anyway!!

That said, with yours, do you mean you've fitting standalone DRO slides/gauges, rather than an all in one solution with a central display thing? That looks like a much cheaper option and I guess I could afford to do one axis at a time over a few months perhaps….

I got the DRO conversion kit for my C3 lathe from Arc and I love it I must say.

[Bob PerkinsParticipant @bobperkins67044]

Hi Jim

Ive fitted a gas spring and DROs to my X2. I bought the gas spring from LMS. The service was good, but don't forget the import duty as well as the posting. Add @ £15 to the bill. There are some photos in my albums. Strangely I've been altering the x axis DRO this evening as I've had problems getting to the x axis locking screw. Next project is to fit a home made power feed to the x axis.

regards

Bob..

[Howard LewisParticipant @howardlewis46836]

Micro Encapsulated Anaerobic Sealant coated hardware has been used in industry for many years.

There is a patch on the thread containing anaerobic sealant encapsulated (like it says) in very small spheres.

As the screw enters the nut, the sealant capsule,s being bigger than the thread clearance, are crushed and broken, liberating the anaerobic sealant. Once the screw has entered into the nut, oxygen is excluded, and so the sealant cures, and locks the thread!

But unlikely to be anything like as effective if reused or moved and repositioned after curing has taken place.

There is nothing to stop you applying an anaerobic thread lock to an uncoated grubscrew on initial installation, and then removing the screw and reapplying sealant at the time of further adjustments.

Use a thread locker, not some of the higher strength sealants , or you risk taking the corners off the Allen socket, or breaking the key!

Howard

[Jim BaxterParticipant @jimbaxter34386]

Thanks for the explanation Howard – fascinating stuff indeed. Every day is a schoolday as they say!

I've think I've got red and blue loctite, but I forget the numbers of them. Will check and see if either seems suitable.

Either way, I think after some meddling just now that the gib grub screws are the least of the worries really. The big problem is the slop in the lead screw brass nut it seems, with no apparent means of compensating for it that I can see.

You can see the brass critters in question in these pics:

One possible idea occurred to me but I've no idea if it's 'doable' or if it would help much/any. I was pondering on the idea of cutting the brass nut in half with hacksaw/bandsaw, effectively giving 2 shallow nuts instead of one large one. Then in between them, I could add some sort of shims to vary the gap between the two nuts. I guess it'd have the effect of being like using 2 hex nuts together against each other to lock something, but with the correct shimming hopefully have the result of taking out the slop but not locking the lead screw of course!

Does that sound like a workable and reasonable plan that should help, or a folly that will mean I can't put it back together as I've destroyed one of my lead screw nuts?

 

Appreciate thoughts on this, thanks

Edited By Jim Baxter on 31/10/2013 22:55:58

Edited By Jim Baxter on 31/10/2013 22:57:22

[Jim BaxterParticipant @jimbaxter34386]

By the way, the pitch on the lead screw is 1.5mm which I think is shallower pitch than a lot isn't it?

Don't think I checked that both x and y were the same but the x axis definitely is.

If I could get delrin replacements for these that would nip it up a bit then I'd be getting my bank details at the ready!

[Jim BaxterParticipant @jimbaxter34386]

Well well well…. I was searching google for info on possible availability of ready made delrin nuts for my machine but I found a page where what I've thought of here has been done basically:

http://www.fignoggle.com/machines/x2mill/howTo-antiBacklashNut.htm

Interesting that on the second one they did, they didn't actually cut right through, but that seems to be preferable from what it says, so I'm extremely tempted to go and try it.

[John Stevenson 1Participant @johnstevenson1]

Posted by Jim Baxter on 31/10/2013 21:32:40:. Currently I get about 8-10 thou backlash on the table!!

Bloody hell, that's brilliant. my old Bridgy used to have about 40 thou and it wasn't adjustable out because the screw had worn in the middle.

If you are expecting zero to a couple of thou I think you are going to be disappointed or will be later if you get things that tight they just start wearing faster.

[Jim BaxterParticipant @jimbaxter34386]

I suppose it's a matter of perspective to be fair, but I do want to get it as nice as I reasonably can without having to spend tons of time or money on it.

One day I'd absolute love to CNC it but the budget for that is a way off. Probably.

I had wondered about converting to ballscrews as a part way prep stage toward that, but I've been reading that ballscrews can be 'worse' than what I already have if the machine is not converted to CNC at the same time.

Doesn't backlash contribute to tool chatter and that sort of thing though, & thus is a desirable thing to reduce as far as you reasonably can? Sorry if that's a stupid question.

[John Stevenson 1Participant @johnstevenson1]

Jim,

Have a read of this thread.

**LINK**

These can be made to replace the nuts you already have or as additional nuts to bolt onto the back of the existing brass nuts with adjusting screws or shims to control the preload.

[Jim BaxterParticipant @jimbaxter34386]

Thanks very much mate – just had a quick skim through and that looks really useful. I think i've got some of the stuff knocking around but not 100% certain. It's a few blocks of sort sort of plastic that seems like nylon or delrin type material but can't be sure if it actually is.

Another means of adjustment I've seen now with the brass nut is to cut a slot in it front to back so that rather than the same sort of tight spot more likely with cutting it down the middle, this allows you to just make the whole thing slightly more snug. Pic is about half way down this page:

http://www.deansphotographica.com/machining/projects/mill/mill.html

Cheers

[Clive HartlandParticipant @clivehartland94829]

The X3 has a split in the brass nut and 2 hex head clamping scews to adjust the pr-load. M4 looks to be a good size for the clamping screws. I cannot get the backlash on my X3 less than about 8 divs on the scale, this prompted me to go DRO which is all I use now and never look at the dials anymore. With DRO's backlash does not matter.

I also found the Gib strip on the Z axis slack and it is now almost at its extreme adjustment., tightening it up did stop a lot of problems.

Clive

[Jim BaxterParticipant @jimbaxter34386]

Thanks for the input Clive.

When you guys mention converting to DRO are you meaning 3 individual and independent devices, the likes of which are about £30-60 or so each on ebay, and just making your own mounts for them, or some sort of self contained kit with a 3 axis combined super fancy display and all the ancillaries?

Be interested to know more info about DRO conversions people have carried out if they're at the budget end of the scale and work well.

Cheers

Jim

[Bob PerkinsParticipant @bobperkins67044]

Jim

My DRO install was a budget job. All came from ARC. Have a look at my photos. This has been an excellent mod an has improve my capability no end.

Bob..

[Russell EberhardtParticipant @russelleberhardt48058]

This is one of the leadscrew nuts I removed from my SX2P mill when I fitted Delrin nuts:

It already had the split to take up backlash. Your bronze/brass nuts are a different design but a similar splitting should help. What holds them in place? From your picture it looks as if they are not firmly fixed in the slot.

I wouldn't fit ballscrews to a manual machine as the reduced friction allows the table to drive the leadscrew so it won't stay where it's put under cutting load.

John, I tried that method of making Delrin nuts but ended up with such a mess that I gave up and bought an acme tap and did the job properly.

Fitting DROs doesn't help backlash but it certainly makes life easier. I wouldn't be without them on my manual mill.

Russell.

Edited By Russell Eberhardt on 01/11/2013 13:56:02

[Clive HartlandParticipant @clivehartland94829]

I used Machine DRO's when I converted, maybe a bit expensive but the easy setting and use is great.

Clive

[Jim BaxterParticipant @jimbaxter34386]

Thanks for the pic of the nut – I think I'll try cutting a slot and grub screws to it tonight since it's something I can easily do.

No, the brass nuts are not properly held solidly in place by any sort of decent method.

They are basically held in a vague suspended position by virtue of being screwed onto the lead screw. They have grub screws (1 on the Y and 2 on the X) which then push them against the surface behind them, and this sort of pins them in place but it seems like a quick & dirty means of doing so.

Plus depending on the sag or whatever of the lead screw as you tighten the grub screw, it will affect how the lead screw aligns (since nothing else supports it along its length) and thus will affect the feel of the handle etc. All seems a bit random & shoddy to me, but I'm worse than a rank amateur so take that opinion with a huge spoonfull of ignorance!

As mentioned, I'm surprised that there's no bracket & bearing at the 'far' end of the x & y lead screws to support them and add to smoothness presumably with the handwheels operation.

Definitely going to look at getting myself a set of budget DROs now anyway. Thanks for the comments on these, and direction toward pics etc. Very useful ta.

Machine DROs would be nice, but a way off I suspect….

[John ShepherdParticipant @johnshepherd38883]

Jim

If you are going to fit DROs I would forget about modifying the nuts and don't get too hung up about the lack of end support for the lead screws. On both lathes and and milling tables (of this size at least) it seems common practice for the end of the lead screw to be free or to be a very loose fit in a support that can hardly be described as a bearing from what I have seen. I suspect that a close fitting bearing at the free end would create more alignment problems if you consider the lateral movement when adjusting the gib strips for example.

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