Gap bed on G4003 or G4003g?

richl said:
My pm1440gs carriage tightens up just after getting to the gap. I've tried everything to figure out what is going on. It has been like that since I took delivery, matt and crew insisted that was normal and it would wear in... 2 years later it's still like that, I dont think wearing in is going to do it. I have suspected the gap being improperly installed but I dont want to pull it and find I cant get it back to where it is now. Its useable now, I'd hate making it worse.
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You would think that the gap was ground assembled to the rest of the bed and not removed afterwards.

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BenW said:
You would think that the gap was ground assembled to the rest of the bed and not removed afterwards.

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Yes, normal procedure would be to fit the gap section and pin it, then grind the beds so everything is aligned.
 
I would think so also... but it's not just alittle out and I am being super anal. It is noticeably tighter. It does not show when I ran a .0005 dti on it though
 
Nothing wrong with being super anal, any form of precision requires some amount of anality.
There has to be an error somewhere. Apart from measuring the vee planes for parallelism, you should be also measuring the outside width across the beds and same for internal width inbetween the vee beds on both the gap bed section and the normal bed to check for discrepancies.
check the thickness of the rear vee flat on both, where the saddle clamp runs also.
 
dsymes said:
Thanks Bob. That makes sense, but is this advice from personal experience a Grizzly or similar lathe? The manual says "Removing the gap may cause the lathe insert to spring slightly out of shape. When re-inserting, there is no guarantee that original alignment and flush mating will be the same." I'm looking for someone who has taken the gap bed out and reinstalled it.

Douglas
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My experience is with helping others with their lathes, old American iron and newer Chinese lathes as well. Cast iron does not spring much, but damaging the mating surfaces or pins during removal makes the parts not key together properly again. My lathe manual has the same message that yours does, and I think they are covering themselves by blaming something "beyond their control" while not blaming the lathe owner. The gap has not been out of my Kent 13x40 lathe so far. The two times I have helped to put a gap back in, the result was perfect alignment of the gap piece with the fixed bed, one was old American iron and the other was a Chinese 12x36. We were very fussy about cleanup and got both of them to fit correctly on the first try. I must admit, however, that mine will be staying in place until I have a job to do with no other options for getting it done. Having friends with bigger lathes and with lathes having the gap piece already removed makes it an easy work around...
 
So you pay for an option that seems to be pretty useless because the piece wont "re-fit" correctly if said optional part is ever removed!!!
 
Latinrascalrg1 said:
So you pay for an option that seems to be pretty useless because the piece wont "re-fit" correctly if said optional part is ever removed!!!
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I don’t think they charge extra for it. I’m pretty sure mine is bondo-ed over and painted as well. It’s more like a feature that’s included because that’s how the patterns they bought or copied 30 years ago were made.
 
Bob Korves said:
My experience is with helping others with their lathes, old American iron and newer Chinese lathes as well. Cast iron does not spring much, but damaging the mating surfaces or pins during removal makes the parts not key together properly again. My lathe manual has the same message that yours does, and I think they are covering themselves by blaming something "beyond their control" while not blaming the lathe owner. The gap has not been out of my Kent 13x40 lathe so far. The two times I have helped to put a gap back in, the result was perfect alignment of the gap piece with the fixed bed, one was old American iron and the other was a Chinese 12x36. We were very fussy about cleanup and got both of them to fit correctly on the first try. I must admit, however, that mine will be staying in place until I have a job to do with no other options for getting it done. Having friends with bigger lathes and with lathes having the gap piece already removed makes it an easy work around...
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Thanks for the further info. I think I've gone from "Oh goody! I can turn oversize pieces every Thursday" to your approach - "no other option".

Douglas
 
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