View Full Version : Gap-bed lathe question

G.A. Ewen
03-30-2003, 12:06 AM
Hi guys, I have just purchased a used gap-bed lathe. It is about 20 years old and in exellent condition. She swings 13" over the bed and about 16" over the gap. The previous owner never used it for large work and can't remember ever taking the gap section out. My question is, will it hurt the machine if I run it with the gap section out all the time? It does not look ask if the gap section adds any strength to the bed but I would like to be sure. All suggestions are appreciated, thanks.

Dave Opincarne
03-30-2003, 12:30 AM
Thrud, you were about to say... http://bbs.homeshopmachinist.net//biggrin.gif

...I'll wait for him.

03-30-2003, 04:39 AM
LEAVE THE GAP PIECE IN! If you take it out, you may never acheive proper alignment of it again. Some european lathes are designed without a gap piece - these are rock solid.

Unless you absolutely have to - don't pick at it! And if you do, don't say you were not warned. http://bbs.homeshopmachinist.net//biggrin.gif

03-30-2003, 08:39 AM
Being the not-so-enthusiastic owner of a South Bend gap bed 10K lathe...I echo Thrud.

Now, I will qualify that a bit to say that I'm sure there must be some gap bed lathes, somewhere, that aren't a problem...but it would be too bad to guess wrong about yours.

03-30-2003, 11:10 AM
I had a Grizzly 12 X 36 gap bed lathe and removed the gap. I had a lot of trouble getting the gap back in and lined up again. The lathe worked fine with the gap out but you limited your travel of the saddle.

With a lot of work I got the gap back in and aligned again. The main problem was with the taper alignment pins. I aligned the gap and clamped it in place. Redrilled and taper pin holes and inserted new larger pins. Also added 2 additional pins. The bottom of the gap also had to be ground on a little to get the height correct. This took days of work.

Today I have a 14x40 with a gap. I do not plan on ever removing the gap as I don't want to go through the experience again.

Hope this helps.


03-30-2003, 02:23 PM
One of my pet peeves is light duty lathes with a gap. Great loss of rigidity in exchange for a feature the machine is generally underpowered to utilize.

03-30-2003, 06:10 PM
I wonder if owners of gap-bed lathes that have never taken the gap out shouldn't run some crazy glue into the joints so that in case they ever are tempted to take it out, they won't be able to, thus ensuring that they have more time to make chips rather than fix the lathe. Just a thought. http://bbs.homeshopmachinist.net//smile.gif

03-30-2003, 06:23 PM
If a gap would be a feature that would be handy but not needed, then i would not get a lathe that has a gap. I have a gap in one of my lathes and i don't like it because the chips cannot fall down in the pan, instead they just collect in the gap. My gap does line up no problem when taking it in and out, but when it is out the carriage is too far away from the chuck, unless the carriage overhanges the bed gap (poor design in my book)and i think the lathe spindle really was not sized to handle work this big. I have taken my gap out one time but never used the machine with it out because of the above mentioned design weaknesses. I have a larger 15" leblond regal lathe but i could use one larger on some occasions. Leblond made a slideing bed lathe, where the entire bed could be cranked out on a lower bed so you can crank out only as far as you need and the machine spindle seems to be beefed up to handle any large work. I have given some thought as to whether or not finding one is practical for me right now, because i think the machine fits a nitch that is perfect if you don't need a large machine very often and floor space is a problem as in my case. Last time i saw one for sale, it was by machinery values in N.J., but first i would like to know if anybody has ever used one and what are the pro's or con's of the machine are.

kap pullen
03-30-2003, 07:19 PM
Rick has it about right.

I have had a machine world 13 x 40 gap bed (jap lathe) for twenty years.
Had a webb 21 x 80 inch gapper.
Had the gaps out of them both a couple times.

Just lightly stone before re-assembly.

There isn't any support @ chuck, as stated with the gap out.
May have to do your gap work with boring bars to keep the carriage well supported.

Everything is a compromise.

Sorry the gap length can't please everyone.
Either it's to long for chuck work, or too short for gap work.

Ain't much in the world that pleases thrud except that little expensive Austrian lathe
and shiney stainless steel.

We have a sliding bed Lablonde at work.
I had to use it twice.
Little clumsey but did the job.


[This message has been edited by kap pullen (edited 03-30-2003).]

03-31-2003, 04:49 AM

Hey, I don't mind hot, loose, intelligent women that adore 400lb. gorillas and like to shower them with expensive tools in exchange for 400Lb. Monkey Love! http://bbs.homeshopmachinist.net//biggrin.gif

And I am kind of partial to real Chocolate milk!

G.A. Ewen
04-01-2003, 04:34 AM
Many thanks for the advice from all of you. It has set me on the right track and will, i'm sure, save me a good deal of grief.