Lathe Bench - Laminated Mdf?

[sbx]

Hey all,

So, I am having a hard time figuring out what I'd like to do for a benchtop for my Southbend 9A. Its has a 42" bed, and horizontal drive. I have a fairly sturdy steel frame for it (came with purchase) that I'd like to re-use, but the top that came with it isn't in good shape, and I'd like to improve on the rigidity.

So, after searching and not finding any cost effective solutions for dimensions I'd like, I thought I may try to fabricate something.

Has anyone attempted to laminate several layers of 3/4" MDF to come up with a hard, think, somewhat flat top?

I was contemplating doing 2-3 layers of 3/4", capped off with formica or better yet some sort of phenolic laminate to cover and seal off the mdf from exposure.

Any thoughts, experiences or advice would be appreciated. I rent a shop right now, so this may not be a permanent solution, but I do want something serviceable and able to function well with my lathe.

Thx,
sbx

 

[Eddyde]

2 or 3 layers would probably work if well supported, as even thick MDF will sag if the span is too great. I recommend laminating top and bottom surfaces as MDF is greatly affected by humidity changes and can bow if only sealed on one side. The other potential problem is bolting to MDF as it will compress over time causing the bolts to loosen. Epoxying in full length bushings can help avoid that problem.
Another approach would be to use a ¾"-1" thick piece of phenolic, it might cost a bit more but much less labor.

 

[francist]

Eddyde has hit the nail on the head, so to speak. MDF will give a nice smooth surface but won't contibute much to rigidity if that's what you're after. If you have access to someone with a planer (for wood), laminating 2x4's on the flat would make a more rigid top with easier opportunity for fasteners. The MDF does have the advantage of increasing weight though, the stuff is heavy.

-frank

 

[ch2co]

I ran a series of 2 x 8's bolted to the top of the metal framework of my stands and then covered that with 3/4 MDF .
You could park a car on top of it, and yes it is flat.

Chuck the Grumpy One

 

[brino]

Hey Grumpy Chuck,

That would be very sturdy.
Do you have any trouble with the MDF absorbing oil and swelling up?
Or did you seal it with something?

-brino

 

[ch2co]

Actually I covered the whole thing with a sheet of 18 ga. galvanized steel before
setting, shimming and bolting down the lathe.

Grumps

 

[RJSakowski]

I would be concerned about dimensional stability of wood products, particularly humidity. I built several lathe benches and use 7" channel for the base on a steel frame. I then covered the top with steel sheet, welded to the top. we go through a lot of exercise to insure that the bed is level to the accuracy of a machinists level, literally a half thousandth/ft to avoid bed twist and the problems that come with it. With a small lathe, you can get away with it. For a 42" lathe, probably not. You may actually be better with a more flexible bench and relay on the rigidity of the lathe bed itself rather than forcing it to follow the contortions of an unstable material. Just my $.02, take it for what it's worth.

 

[4GSR]

My 9A x 42" bed SBL has been setting on a bench/cabinet I built when I was 15 years old nearly 40 years ago. It was made from some left over 5/8" thick particle board underlayment flooring from the house dad built for the family. The top has two layers of 5/8" thick particle board on it. Looks like crap now but is in good structural shape for the 4 or 5 times it has been moved over the years. Probably has close to 200 lbs of tooling stuffed up inside the cabinets in the base besides the weight of the lathe itself.

 

[Andre]

If you laminate MDF, I wonder if an edge of angle iron sandwiched in might help with sagging.

 

[hman]

I have a double layer of 3/4" MDF under my Grizzly 9x20 lathe. The lathe has a drip pan and I gave the MDF a couple coats of shellac (about 4 coats on the very thirsty edges). The MDF is atop a very sturdy 2x4 frame. Seems to be holding up well so far.

As for bolt strength of the MDF ... I "just snugged" a 1/2" bolt, with largish washers a lock washer and nylock nut, at the headstock end of the bed. The tailstock end has a similar arrangement, except that I only collapsed the lock washer about half way. This holds the bed in place, without imposing twisting forces on the bed.

The attached photo shows the table just before I slid the lathe over from the one it was on when I bought it used.