# Gap bed on G4003 or G4003g?



## dsymes (Apr 23, 2019)

Having just set my G4003g on stands and epoxied the threaded rods into the concrete (I got a friend to weld some 3/8 angle to the sides of the stands as a number of others here have also done),  I've been going over the manual with more diligence as I get closer to firing up the beast.  I notice that the manual warns that taking out the gap bed may upset the alignment of the ways.  Has anyone here removed and replaced the gap, and what has your experience been?

Douglas


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## richl (Apr 23, 2019)

Unless it's absolutely essential, dont. I removed the gap on an enco 13x40. I got the gap back on and adjusted, but I wouldn't do it on my pm1440gs. 

My 2 cents worth


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## kd4gij (Apr 23, 2019)

I do not have a grizzly lathe. But at work we have a 20x80 gap bed and a 30x120 gap bed lathe and the gap comes out all the time. Just indicate it in when reinstalling. What is the point of having a gap bed if you can't remove it.


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## jwmay (Apr 23, 2019)

I had an old machinist tell me to never remove the gap. He delivered it with one of those knowing thousand mile stares you see so often in Army movies. Or maybe like Aunt Matilda when warning the kids not to swim until 45 minutes after eating. At any rate, I figure they wouldn’t keep making them that way if it was a method of sure destruction.  Then again, I’ve never taken the gap out of mine either.


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## Bob Korves (Apr 23, 2019)

If you take your time taking the gap piece out carefully, and then clean everything scrupulously before going back together, and then don't beat on it with a hammer trying to get it to fit, all will be well.  The gap must match with the bed perfectly, which mean no trash or chips -- ZERO!  It should fit perfectly BEFORE you tighten the bolts down.  If you try to force it once, it will probably never fit correctly again.


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## dsymes (Apr 24, 2019)

Bob Korves said:


> If you take your time taking the gap piece out carefully, and then clean everything scrupulously before going back together, and then don't beat on it with a hammer trying to get it to fit, all will be well.  The gap must match with the bed perfectly, which mean no trash or chips -- ZERO!  It should fit perfectly BEFORE you tighten the bolts down.  If you try to force it once, it will probably never fit correctly again.


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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## fitterman1 (Apr 24, 2019)

dsymes said:


> Having just set my G4003g on stands and epoxied the threaded rods into the concrete (I got a friend to weld some 3/8 angle to the sides of the stands as a number of others here have also done),  I've been going over the manual with more diligence as I get closer to firing up the beast.  I notice that the manual warns that taking out the gap bed may upset the alignment of the ways.  Has anyone here removed and replaced the gap, and what has your experience been?
> 
> Douglas


I dont have a g4003g, but i wouldn't think taking the gap out would cause a problem.
Most of the lathes I've worked on had parallel or tapered pins to realign the gap when reassembling. Think cleanliness.
If you have space somewhere, i suggest clocking your gap to make sure its in alignment and then fitting your own  tapered pins for fitting it back in. Just make sure they're installed in a solid section of webbing if possible.
I think the manual shouldn't be suggesting you not remove it, because it was made to be removed. And they are concerned with the users ability to reset it.
Can't help you much more, but thats my thoughts.
Cheers Alby


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## darkzero (Apr 24, 2019)

fitterman1 said:


> I dont have a g4003g, but i wouldn't think taking the gap out would cause a problem.
> Most of the lathes I've worked on had parallel or tapered pins to realign the gap when reassembling. Think cleanliness.
> If you have space somewhere, i suggest clocking your gap to make sure its in alignment and then fitting your own  tapered pins for fitting it back in. Just make sure they're installed in a solid section of webbing if possible.
> I think the manual shouldn't be suggesting you not remove it, because it was made to be removed. *And they are concerned with the users ability to reset it*.
> ...



I aslo think that is the reason why Grizzly recommends not removing the gap, from a customer service stand point, they don't want to deal with all the users calling in who are unable to get it realigned properly.

The G4003/g is based on a very common 12x design. It too should have 2 tapered pins & a set screw pusher at the headstock end.


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## BenW (Apr 24, 2019)

I removed the gap on my machine (Taiwanese 13*something) to clean out the rust, and definitely regret doing so. There are 2 taper pins that are supposed to align it, but the 2 flycut faces are rough enough that it refuses to go back where it should. If I insert the taper pins it moves further out of alignment than without them installed. I tried for days to get the dam thing back, stoning, cleaning and tapping, but had to eventually settle for 0.01mm (3-4 tenths I think) high on the front v and about the same ammount low on the rear flat. The carriage noticeably gets a bit more snug when I move it over the gap. I'll have to revisit the problem soon, worst case I think I'll permanently tram it with epoxy. 

Sent from my LYA-L29 using Tapatalk


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## richl (Apr 24, 2019)

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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## BenW (Apr 24, 2019)

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.


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

Sent from my LYA-L29 using Tapatalk


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## fitterman1 (Apr 24, 2019)

BenW said:


> You would think that the gap was ground assembled to the rest of the bed and not removed afterwards.
> 
> Sent from my LYA-L29 using Tapatalk


Yes, normal procedure would be to fit the gap section and pin it, then grind the beds so everything is aligned.


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## richl (Apr 24, 2019)

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


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## fitterman1 (Apr 24, 2019)

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.


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## Bob Korves (Apr 24, 2019)

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


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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## stupoty (Apr 24, 2019)

Keith Fenner has a video on re fitting his gap piece.






Stu


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## Latinrascalrg1 (Apr 24, 2019)

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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## Bob Korves (Apr 24, 2019)

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!!!


I think that statement is considerably over simplified...


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## jwmay (Apr 24, 2019)

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!!!


 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.


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## dsymes (Apr 24, 2019)

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...


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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## Tozguy (Apr 24, 2019)

I have a gap bed lathe but don't need the gap so it stays put. It sounds like the gap piece is not designed to be an on-off feature like a switch.
It is more like a tab on an aluminum beer can. So putting the gap piece back in is like welding the tab back to seal a beer can. It can be done but...


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## f350ca (Apr 24, 2019)

I'd be very afraid removing the gap from an import lathe. Who knows how big a hammer they used to install it BEFORE it was ground.
My bigger lathe was made in Poland with much more care and I'd never think of removing it. 

Greg


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## Latinrascalrg1 (Apr 24, 2019)

Bob Korves said:


> I think that statement is considerably over simplified...


Is it Really?   I mean just going by this very small sampling of comments from the machining world population concerning the topic of removing and correctly replacing a gap bed insert, which include comments made by you, the ONE lesson LEARNED here is that Removing that insert should only be done if NO OTHER OPTIONS are available to you!


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## Superburban (Apr 24, 2019)

I have the shopfox equivalent of the G4003G, I have removed the gap about 10 to 12 times. The first few times, I was real anal about getting it back perfect, and alinged with the dial indicator, for straightness. After the 3 or so time, I just clean, and put it back making sure there is no noticeable misalignment were the gap meets the bed ways. After I install it, I make a cut, where the saddle is riding from the gap, up to the headstock, then check the diameter at both ends, it has been prefect every time.


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## westerner (Apr 24, 2019)

f350ca said:


> Who knows how big a hammer they used to install it BEFORE it was ground.


I have the Birmingham equivalent of the Grizzly mentioned. I have never removed the gap. I HAVE torn the thing down to clean and inspect. After seeing what I saw, I will go with the post quoted above


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## Buffalo21 (Apr 25, 2019)

I have a Jet 14x40, I’ve had the gap piece out about 50-75 times in the last 8-10 yrs, I’ve never had an issue with it going back in, wipe the area clean, reinstall the piece.


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## Cadillac (Apr 25, 2019)

I also have a optimum 14x40 with a gap that I have not needed to remove yet. My take on the gap is if your lathe is properly setup/leveled and straight it shouldn’t be a problem. 
 Pull the gap and your bed is tweaked it’s probably gonna be a bear to get realigned. 
 I would think if you indicate it before you remove and when installing make sure all your surfaces are clean reindicate it you shouldn’t have much troubles.


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## epanzella (Apr 25, 2019)

I read some where that the problem of alignment arises when the gap was originally assembled with a chip or some grit under it and then ground. When you try to install it without the grit it won't line up. I've never taken the gap out of my G4003G and don't plan to. I'm a chicken!


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## darkzero (Apr 26, 2019)

stupoty said:


> Keith Fenner has a video on re fitting his gap piece.
> 
> 
> 
> ...



Keith also shows removing the gap on his Rutland lathe which is the same basic design as the G4003/g. He briefly shows why people are scared to remove the gap (quality issues).

I don't agree that the gap should never be removed but I can understand the reasoning for it. With that said I have a PM1236, which again is the same basic design lathe. I too am too chicken to remove mine & I'll never remove it unless the day comes where I absolutely really need to. I don't feel like finding out how much bondo is holding the damn thing on anyway.


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## stupoty (Apr 26, 2019)

darkzero said:


> Keith also shows removing the gap on his Rutland lathe which is the same basic design as the G4003/g. He briefly shows why people are scared to remove the gap (quality issues).
> 
> I don't agree that the gap should never be removed but I can understand the reasoning for it. With that said I have a PM1236, which again is the same basic design lathe. I too am too chicken to remove mine & I'll never remove it unless the day comes where I absolutely really need to. I don't feel like finding out how much bondo is holding the damn thing on anyway.



I'm reading this thread as an interested observer, I'm always liking the idea of a gap bed lath or sliding gap lathe,  my first lathe was a small older lathe and has a fixed gap area which was quite handy.

I can see the difference between the old iron lathe keith has and the newer one with the rough mating surfaces.

Stu


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## Cadillac (Apr 28, 2019)

This is how I’d expect my gap to come off and how it should mate together. Are my expectations to high


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## FOMOGO (Apr 28, 2019)

In a word,YES, but that is so cool. Thanks for posting. Mike


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