By continuing to use this site, you agree to our use of cookies. Find out more
Forum sponsored by:
Forum sponsored by Allendale Jan 24th

Colchester Bantam 2000

All Topics | Latest Posts

Search for:  in Thread Title in  
needleworks18/02/2018 18:06:13
8 forum posts

The play in my cross slide is starting to really annoy me now so I reckon it's about time to replace the nut, or the screw, or both if that's what it needs. I assume it's going to be an acme thread, but on measuring, I can't decide if it's imperial or metric !

I have measured it at 14.2 mm x 2.5 in metric, on the imperial side it measures .559 x 10 tpi.

Has anyone previously done this fix that could give me some advice?

Thanks in advance guys

Mick B118/02/2018 19:08:48
1776 forum posts
91 photos

.559" is 3 1/2 thou down from 9/16. My guess is imperial.

Mike Poole18/02/2018 19:13:10
avatar
Moderator
2810 forum posts
66 photos

Does the scale on the handwheel not give away the pitch?

Mike

needleworks18/02/2018 20:03:40
8 forum posts
Posted by Mike Poole on 18/02/2018 19:13:10:

Does the scale on the handwheel not give away the pitch?

Mike

On the Bantam you have the luxury of both, pull the dial out it reads metric, push it in it reads imperial.

needleworks18/02/2018 20:07:34
8 forum posts
Posted by Mick B1 on 18/02/2018 19:08:48:

.559" is 3 1/2 thou down from 9/16. My guess is imperial.

I thought of 9/16, but I can't find a left hand acme tap 9/16 x 10 tpi anywhere on the net

Chris Evans 618/02/2018 20:35:57
avatar
1781 forum posts

Look for leadscrew makers on the net. Plenty about I bought a 1 metre length of 16mm left hand screw and matching nut very cheaply from Automotion Components. A bit of simple machining to cut the threaded part of the original screw off and spigot it onto the remaining part secured with a roll pin and a dab of Loctite. If the pitch is correct don't get to hung up about the diameter if replacing the nut. I got enough to make three cross slide screws and a nut for around £50/60.

Pete Rimmer18/02/2018 21:48:04
810 forum posts
50 photos
Posted by needleworks on 18/02/2018 20:07:34:
Posted by Mick B1 on 18/02/2018 19:08:48:

.559" is 3 1/2 thou down from 9/16. My guess is imperial.

I thought of 9/16, but I can't find a left hand acme tap 9/16 x 10 tpi anywhere on the net

You won't and it probably wouldn't help you anyway. IIRC the Bantam cross slide screw is a 2-start thread. .100" pitch but 5tpi lead.

Mike Poole18/02/2018 21:51:57
avatar
Moderator
2810 forum posts
66 photos
Posted by needleworks on 18/02/2018 20:03:40:
Posted by Mike Poole on 18/02/2018 19:13:10:

Does the scale on the handwheel not give away the pitch?

Mike

On the Bantam you have the luxury of both, pull the dial out it reads metric, push it in it reads imperial.

Ah that makes life a bit more complicated.

Mike

Gute Fahrt17/10/2020 11:17:51
45 forum posts
1 photos
Posted by Chris Evans 6 on 18/02/2018 20:35:57:

Look for leadscrew makers on the net. Plenty about I bought a 1 metre length of 16mm left hand screw and matching nut very cheaply from Automotion Components. A bit of simple machining to cut the threaded part of the original screw off and spigot it onto the remaining part secured with a roll pin and a dab of Loctite. If the pitch is correct don't get to hung up about the diameter if replacing the nut. I got enough to make three cross slide screws and a nut for around £50/60.

I was wondering was there any centres on the leadscrew or whatever they are called to accurately place the bar between two centres?

Emgee17/10/2020 11:59:28
1764 forum posts
237 photos

You can easily confirm the pitch of the leadscrew by fitting a Dial gauge between the tool post and a chuck mounted rod, do 1 complete revolution of the handwheel and read the gauge, you will have to take up any backlash before doing the test revolution.

Emgee

Chris Evans 617/10/2020 12:56:30
avatar
1781 forum posts

As I recall there are no centres in the replacement lengths of leadscrew. The threads are formed by rolling and I have found them to be very accurate. I simply cut off the required amount and held it in a 5C collet to turn the ends to suit. I made two cross screws and nuts from what I bought and still had enough over to make a third screw. After 5 or 6 years of regular use there is still no play in the first one I fitted so the spares are still on the shelf. I did add an additional oil point to lubricate the screw a bit better than original design.

Gute Fahrt18/10/2020 13:37:38
45 forum posts
1 photos
Posted by Chris Evans 6 on 17/10/2020 12:56:30:

As I recall there are no centres in the replacement lengths of leadscrew. The threads are formed by rolling and I have found them to be very accurate. I simply cut off the required amount and held it in a 5C collet to turn the ends to suit. I made two cross screws and nuts from what I bought and still had enough over to make a third screw. After 5 or 6 years of regular use there is still no play in the first one I fitted so the spares are still on the shelf. I did add an additional oil point to lubricate the screw a bit better than original design.

thanks for the information. The collet idea would seem to solve the problem of centering things.

All Topics | Latest Posts

Please login to post a reply.

Magazine Locator

Want the latest issue of Model Engineer or Model Engineers' Workshop? Use our magazine locator links to find your nearest stockist!

Find Model Engineer & Model Engineers' Workshop

Latest Forum Posts
Support Our Partners
emcomachinetools
EngineDIY
Warco
cowells
ChesterUK
Eccentric July 5 2018
Eccentric Engineering
Subscription Offer

Latest "For Sale" Ads
Latest "Wanted" Ads
Get In Touch!

Do you want to contact the Model Engineer and Model Engineers' Workshop team?

You can contact us by phone, mail or email about the magazines including becoming a contributor, submitting reader's letters or making queries about articles. You can also get in touch about this website, advertising or other general issues.

Click THIS LINK for full contact details.

For subscription issues please see THIS LINK.

Digital Back Issues

Social Media online

'Like' us on Facebook
Follow us on Facebook

Follow us on Twitter
 Twitter Logo

Pin us on Pinterest