Bridgeport leadscrew adjustment.

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Bridgeport leadscrew adjustment.

This topic has 8 replies, 6 voices, and was last updated 26 December 2011 at 21:36 by Alexander Moss.

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20 November 2011 at 02:29 #78185
Alexander Moss
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@alexandermoss
I I get about 1/3 turrn backlash on main table feed; anyone know how to adjust this? Machine is otherwise very good, if a bit stained. Though the power feed to table seems to have duff electronics. It is the version with the 600W dc motor. How can this be checked and who could fix it? Or is it easier to buy a new, (expensive), power feed unit?

Roy Moss
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20 November 2011 at 02:29 #11852
Alexander Moss
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@alexandermoss
How do I adjust for backlash?
20 November 2011 at 08:39 #78192
ady
Participant
@ady
With one nut, if you eliminate backlash in direction A, you will have backlash in direction B

I have pultra zero backlash nuts in my piccies, they are from a lathe built to make prototype parts for missiles in the 1960s

You need two nuts, one covers each direction of travel.

Only a brand new nut and leadscrew gives zero backlash.

If
the middle of the leadscrew is worn even slightly then even the zero
backlash system doesn’t work over the length of the leadscrew.

The best anti backlash nut is the one which sits on your shoulders, you have to think about a job as it progresses, which can be a pain but it is the best anti backlash nut an amateur posesses.

Edited By ady on 20/11/2011 08:48:21
20 November 2011 at 08:51 #78193
john fletcher 1
Participant
@johnfletcher1
I have circuit diagram and other details of the Bridport electronic controller for the power cross feed, if that is any help, would you like copies ?. Can one send personal message on this site? if so, send me one with your phone number and address.
20 November 2011 at 09:58 #78196
Anonymous
When my Bridgeport table 6F power feed failed, it turned out to be a dirty and worn commutator in the DC motor, not the electronic controller. It might be worth looking at the motor first.

Again, on my Bridgeport, the table feedscrew has anti-backlash nuts ‘accessible’ from the lefthand side of the saddle. If needs be I can scan and post the relevant page from the manual. However, as ady correctly says, if the leadscrew is worn unevenly then the anti-backlash nuts don’t really help. I live with about a fifth of a turn of backlash on the table. But I did fit a Newall DRO to the Bridgeport, so the backlash doesn’t bother me.

Regards,

Andrew
20 November 2011 at 10:05 #78198
Hugh Gilhespie
Participant
@hughgilhespie56163
Hi Roy

This link has a very good discussion on adjusting the backlash on a Bridgeport.

Regards, Hugh
20 November 2011 at 11:33 #78203
KWIL
Participant
@kwil
Roy,

Note that the correct factory set up is NOT zero backlash, it is 0.004-> 0.005″ (0.10->0.12mm)

You will not get Zero backlash, only with precision leadscrews and ball nuts will you approach that!

Best to fit a DRO and just minimise the mechanical backlash the best you can, like Andrew I use a Newall system on mine.

K
20 November 2011 at 18:23 #78240
ady
Participant
@ady
Independent DRO is the best route IMO because with a little thought it completely eliminates the problems of backlash
26 December 2011 at 21:36 #80533
Alexander Moss
Participant
@alexandermoss
Thanks for the replies; plenty to try out, especially on the table backlash. but my electronic skill is not up to repairing the table drive control. I use a 3ph convertor, and It could be that I need to check that the table control is taking power from the true 415V supply, rather than from the artificial phases. If that fails, I will look for a competent specialist, or do without autofeed.

Regards,

Roy moss
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