Most older wood lathes have around 36″ max between centers. Anyone who has made chairs knows that this is a limiting factor. Most larger rocking chairs have 40″-42″ back post. I have made do with some pretty stupid and unsafe rigs to turn longer posts but finally decided on a more permanent solution for the short tool issue.
The lathe I modified here is a 1970’s era Delta picked up from Craigslist a couple years back for $100. It had bushing problem on the Reeves drive and a three phase motor, both were easy fixes. This lathe had exactly 37″ between centers before modification.
The extension was made in place on the lathe to assure alignment and fit and would recommend you do the same. The lathe bed is cast iron and brittle, you would not want any undue pressure from the mounting bolts created by a bad fit.
I used 1/2″ by 2″ bar stock all the parts of the extension. Bore the mounting holes in the side pieces. Align and clamp them to the lathe bed then bore thru the bed sides and install the bolts.There are two gussets between the side supports. These have a notch in the center to allow the banjo and tail stock clamping mechanisms to pas thru. The notch cuts don’t have to be pretty.The first gusset has a single bolt thru the bed. Bore and install the bolt, then tack weld the gusset to the side bars.Tack in the second gusset then solid weld both in place.The two extension bed ways were clamped to a flat surface, aligned and two scraps tack welded to hold them. Set them in place on the lathe (I milled a piece of wood to set in the bed gap to help with this), align end of the ways closest to the lathe bed and tack weld in place. Remove the scrap closest to the bed and use a straight edge from the lathe ways onto the extension to align the far end and then tack it. From underneath, weld the ways solid, also a couple of short welds on the edges of the ways on the topside. Don’t go too crazy with the welding, the more heat from welding the more warping. I just did a few 1″ long welds spaced evenly. After all has cooled remove the second scrap and grind away the welds. I am using 1/2″ thick stock here because the ways of the lathe are the same. If these are not the same the tail stock would not clamp properly.
The completed extension cleaned up and painted.
I know most woodworkers don not seem to venture too far in metal work (or vise-versa for that matter). If you have an older lathe and wanted something like this made, any metal fab shop could make one.
How long could you make one of these? The one above extends the bed 10″; I would be uncomfortable with anything over 12″. The longer the extension the more pressure exerted on the cast portion of the bed. Of course, if you are in the business of making those terrifying YouTube videos turning a tree trunk, by all means, make it longer!!
Thanks for sharing this. I have basically the same 1970’s era Delta lathe (also from Craigslist). This is a mod that could work for me. But I think I will need to build up some courage to give it a try! …Tom
I have an old cast iron lathe that was actually used for spinning aluminum kettles on and It only had 21 inches between centers. So I built an extension out of some 2 inch thick plywood with a 3rd leg for support, so now I have a 36 in bed.
Eclectic Mechanicals 
Thanks for sharing this. I have basically the same 1970’s era Delta lathe (also from Craigslist). This is a mod that could work for me. But I think I will need to build up some courage to give it a try! …Tom
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Looks good, Will. Hey, maybe starting on the trestle table build soon.
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I have an old cast iron lathe that was actually used for spinning aluminum kettles on and It only had 21 inches between centers. So I built an extension out of some 2 inch thick plywood with a 3rd leg for support, so now I have a 36 in bed.
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