Drop bed lathe

Suzuki4evr said:
My lathe has one and I removed and replaced it a few times,no problem. BUT,the desighn suck,because with it you remove the last section of rack aswell and therefore the apron can't go further than that point and 90% of the time it needs to. So most of the time I end up putting back the piece of bed without having done the job because the toolholder could not reach and I had to make other plans using the mill or rejecting the job.

Do you guys have the same problem?
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No. The carriage pinion isn’t that far to the left, I still have the compound that can reach a ways over and if the gap is out I’ve got a large piece in - which often means some creative tooling is needed. Example: I was skimming a wheel that was 21” diameter and I’m good for 21.25“ dia in the gap - that gave me 0.12” clearance - the challenge was not enough cross slide travel - I ended up swinging the compound around to travel the tool out further. The point being you may need a bit of a work around - use a boring bar to reach over, perhaps you’ll need to run in reverse.
 
Turning a large OD near the chuck can be a challenge even without having a gap or removing one. One needs to be creative in getting the tool bit to the work. I have reversed the compound and used a boring bar to reach.

If I had to do it often, I would make an adapter to place the QCTP further outboard and ahead of the carriage. It would be far less rigid, but allow light cuts on a workpiece larger in diameter than the swing over the carriage.

I think that the gap is intended for boring a large diameter gear or sprocket. When we use it to turn or face a large OD object, we are exceeding the design parameters.
 
For sure, the best solution is to get a bigger lathe. :) I'd like that. I have 40,000 lbs of old iron now, but I think "just one more" piece would be good (it never ends, I'm getting tight on space right now, but if an opportunity came along . . . . . . ?).
 
BROCKWOOD said:
There are 'Gap Bed' & then there are, 1 step further, 'Adjustable Gap'. With this design, simply adjust the entire bed in or out as needed! NOTES: I probably got the actual name wrong on this version. This version will require more space lengthwise.
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That is called a "sliding bed gap lathe".
 
Chipper5783 said:
No. The carriage pinion isn’t that far to the left, I still have the compound that can reach a ways over and if the gap is out I’ve got a large piece in - which often means some creative tooling is needed. Example: I was skimming a wheel that was 21” diameter and I’m good for 21.25“ dia in the gap - that gave me 0.12” clearance - the challenge was not enough cross slide travel - I ended up swinging the compound around to travel the tool out further. The point being you may need a bit of a work around - use a boring bar to reach over, perhaps you’ll need to run in reverse.
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I had to be very creative a few times,but it makes it very difficult and you have problems with a nice finnish with long tool stickout sometimes. I do make plans as problems arise but it eats up valuable time to do so.
 
When replacing the gap, it's easier to get perfect alignment off the taper pins if you put a good coat of way oil on the contact surfaces. The gap will "float" on the oil film until tightened right where it belongs.

Gap was meant to be removed, if you need the swing, use the feature. I will not fear, for fear is the mind-killer.
 
This is interesting to me. One of the manuals for my lathe(Chinese 13x40) says due to the precision with which the gap section is installed and ground at the factory, if it is removed it’s not recommended to try to reinstall it.

it appears that one of the PO’s of my lathe have removed and reinstalled it, however, and there is a “step” in the ways enough to hear when the 3D printed way wiper passes over it.
 
Can you tell how much that affects the actual accuracy?
I think I'd be inclined to take the gap filler out, ultra clean and debur.
Are there any jack screws to aid in adjusting?
On my Chinese 1440 that chunk looks heavy and therefore likely to get dinged when trying to put it back in. Some way of very gently handling?
 
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