Warco WM18 lead screws upgrade

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Warco WM18 lead screws upgrade

This topic has 31 replies, 11 voices, and was last updated 12 January 2020 at 19:07 by petro1head.

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26 December 2019 at 11:06 #443334
petro1head
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@petro1head
Hope everyone had a great Christmas day yesterday.

I have a WM18 mill and just wondering if there is an upgrade for the X and Y leadscrews.

Now, to be honest, I am probably being fussy but would love to reduce the back lash without binding the threads with the conventional ACME setup to get an acceptable tollerance

Looking on the internet I have seen people using ball screws.

Just wondering if anyone has done this, not nessessarily to a WM18
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26 December 2019 at 11:06 #27028
petro1head
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@petro1head
26 December 2019 at 12:15 #443350
Paul Lousick
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@paullousick59116
Ball screws are a common upgrade when converting a mill to CNC. They are available with anti-backlash nuts.

Paul.
26 December 2019 at 13:32 #443362
not done it yet
Participant
@notdoneityet
Are they really that bad? Is it the thread fitting between nut and screw, or is there ‘slop’/clearance in the other parts of the mechanism?

I realised how poor my first lathe was, particularly after I changed to an approx 60 year old British built machine.

Backlash is not a problem until it becomes excessive – and while anti-backlash nuts are good, they are an unnecessary luxury on a manual machine IMO.
26 December 2019 at 15:19 #443371
Journeyman
Participant
@journeyman
On my much smaller WM14 the lead-screw nuts are adjustable by virtue of a split in the nut which can be adjusted by tightening a couple of allen headed bolts. These are not evident without disassembly, I don't know if the WM18 is fitted similarly. On mine much of the backlash comes from the handle end and can be adjusted to take up the slack.

John
26 December 2019 at 15:36 #443374
petro1head
Participant
@petro1head
Posted by Journeyman on 26/12/2019 15:19:22:

On my much smaller WM14 the lead-screw nuts are adjustable by virtue of a split in the nut which can be adjusted by tightening a couple of allen headed bolts. These are not evident without disassembly, I don't know if the WM18 is fitted similarly. On mine much of the backlash comes from the handle end and can be adjusted to take up the slack.

John

I am curious re the handle, what is you did to improve things
26 December 2019 at 16:29 #443377
Journeyman
Participant
@journeyman
On the WM14 there is only one handle on the X-axis and I found that by tightening the nyloc nut at the centre of the handle I could remove quite a bit of the backlash from this axis. It might be different with a handle at each end like yours. Similarly with the Y-axis handle some slack can be removed by tightening the nut.

The adjustment on the lead-screw nuts really needs the table removing to get at them. The larger of the two is the X-axis nut. The small holes take M3 allen head bolts to squeeze the slot up

John

Edit: Add image

Edited By Journeyman on 26/12/2019 16:33:49
26 December 2019 at 17:36 #443390
Mike Poole
Participant
@mikepoole82104
A backlash eliminator is useful as it will allow climb milling which will usually give a better finish. Ball screws should be backlash free and allow people to use stepper motors without feedback to position reasonably accurately. Even with feedback that is only monitoring shaft rotation then you need to guarantee that the shaft position relates to the slide position. NC machines often had inductosyn feedback which is independent of screw position but now we have various flavours of DRO which could provide accurate feedback if required.

Mike
26 December 2019 at 22:59 #443428
Enough!
Participant
@enough
Couple of points with respect to ball-screws. I looked at fitting these to my WM16 lookalike some time ago.

– I found it would require machining of the table and cross-slide to fit them. That meant either having another mill/suitable proxy or buying spare parts that I could machine on the original mill before fitting. I chose the second path but good old Busy Bee Tools (Canada) let me down. Again.

– I questioned – in several places – whether there was any possibility of the ball-screws back-driving. I received a positive "No" ….. and a positive "Yes". Since I went off the idea (see above) I never did follow up.
27 December 2019 at 06:56 #443440
JasonB
Moderator
@jasonb
Probably easier to fit a DRO then you don't need to worry about backlash compensation when using the handwheel dials.
27 December 2019 at 08:11 #443443
John Haine
Participant
@johnhaine32865
I have a ballscrew on my Super 7 CNC conversion. If you push the slide without the stepper attached the screw is happily turned by the nut.
27 December 2019 at 14:18 #443486
Michael Gilligan
Participant
@michaelgilligan61133
Posted by John Haine on 27/12/2019 08:11:26:

I have a ballscrew on my Super 7 CNC conversion. If you push the slide without the stepper attached the screw is happily turned by the nut.

.

Out of curiosity, John … What is the pitch ?

MichaelG.
27 December 2019 at 14:36 #443488
Ron Laden
Participant
@ronladen17547
I have 0.008" backlash (going by the handwheel dials) on both the X and Y and it always bothered me as being too much and something I needed to try and reduce, but having fitted 3 axis DRO,s its now something I dont worry about.
27 December 2019 at 15:01 #443494
Enough!
Participant
@enough
Posted by John Haine on 27/12/2019 08:11:26:

I have a ballscrew on my Super 7 CNC conversion. If you push the slide without the stepper attached the screw is happily turned by the nut.

Rather what I suspected at the time …. that the answers I got depended on whether the user's mill was cnc or manual.
27 December 2019 at 16:00 #443501
Alistair Robertson 1
Participant
@alistairrobertson1
A few years ago a friend of mine acquired a scrapped Bridgeport CNC mill. He was busy removing the ball-screws to fit his manual machine to eliminate the back-lash.

I said I didn't think it was a good idea as there would be no self locking of the table. He didn't believe me and could see no problem.

A few weeks later I visited him and lo and lo and behold he is removing the ball-screws and re-instating the original acme screws. He sheepishly agreed that I was right and later confessed he had been machining a cylinder head for a customer when the cutter grabbed and with nothing to prevent the table moving under the cutter power the head was destroyed. He had to buy a new head for the customer at more than £1000!

Lesson learned the hard way!
27 December 2019 at 18:23 #443515
Enough!
Participant
@enough
Well, as Michael was alluding to, I assume, whether it will back-drive does depend on the lead-angle/pitch of the screw … just like a regular screw thread. Trouble is, when I looked into it there was a pretty limited range available in this respect at sensible, hobbyist prices.

Edit to change "sensible hobbyist" to "sensible, hobbyist"

Edited By Bandersnatch on 27/12/2019 18:24:42
27 December 2019 at 18:43 #443517
petro1head
Participant
@petro1head
Well for the moment i think i am going to leave it as it is, instead a bit of dismantling, checking, cleaning etc and see how things are after that.

instead of ball screws, if i find the existing ACME nuts needs replacing whats the best material to use?
27 December 2019 at 23:00 #443556
Michael Gilligan
Participant
@michaelgilligan61133
Posted by Bandersnatch on 27/12/2019 18:23:09:

Well, as Michael was alluding to, I assume […]

.

Quite right, Sir

… what a sensible hobbyist you are !!

Perhaps unsurprisingly, the people who supply such things have some advice on the matter:

**LINK**

How to determine if a screw will back drive

MichaelG.
28 December 2019 at 00:00 #443561
not done it yet
Participant
@notdoneityet
Posted by petro1head on 27/12/2019 18:43:41:

if i find the existing ACME nuts needs replacing whats the best material to use?

Somehow, I doubt you would find the existing nuts are actually ACME.
28 December 2019 at 01:51 #443563
Enough!
Participant
@enough
Posted by Michael Gilligan on 27/12/2019 23:00:52:

Quite right, Sir

… what a sensible hobbyist you are !!
28 December 2019 at 06:22 #443568
petro1head
Participant
@petro1head
Posted by not done it yet on 28/12/2019 00:00:46:

Posted by petro1head on 27/12/2019 18:43:41:

if i find the existing ACME nuts needs replacing whats the best material to use?

Somehow, I doubt you would find the existing nuts are actually ACME.

God knows, something i know nothing about if i was honest

Edited By petro1head on 28/12/2019 06:23:48
28 December 2019 at 06:28 #443569
Ron Laden
Participant
@ronladen17547
Petro, have you considered DRO, s adding them to mine was the best thing I have done to the mill.

Edited By Ron Laden on 28/12/2019 06:35:03
28 December 2019 at 09:10 #443583
petro1head
Participant
@petro1head
Posted by Ron Laden on 28/12/2019 06:28:22:

Petro, have you considered DRO, s adding them to mine was the best thing I have done to the mill.

Edited By Ron Laden on 28/12/2019 06:35:03

I have x,y and z dro
28 December 2019 at 09:23 #443584
Ron Laden
Participant
@ronladen17547
Posted by petro1head on 28/12/2019 09:10:33:

Posted by Ron Laden on 28/12/2019 06:28:22:

Petro, have you considered DRO, s adding them to mine was the best thing I have done to the mill.

Edited By Ron Laden on 28/12/2019 06:35:03

I have x,y and z dro

Sorry, didnt realise you had DRO,s, so it is a case of just wanting to reduce the backlash to a minimum..? what amount of backlash are you getting at the moment.?
12 January 2020 at 15:29 #446139
petro1head
Participant
@petro1head
Sorry for the late reply. I am getting about 90 deg on the handle

i have re thought thing and am still thinking about a ball lead screw for the Z axis. The would mainly to make the up/down of the head easier
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