Do current Powermatic 18" bed extensions fit older model 3520A lathes?

[Brad Winesett]

Just wondering if anyone has purchased a Powermatic 18" bed extension (6294727B) for a Model 3520A? My manual lists the extension as 6294727 without the "B" at the end. I know the current extensions won't mount low since the 3520A doesn't have the holes in the legs. But will the new extensions mount at the end of the existing bed to increase spindle turning length?

I called Powermatic and they said no, but the gentlemen helping me did not sound very sure about it. On Amazon, someone asked this same question and 2 people replied that it did work when mounting at the top of the 3520A. Just wanted to see if anyone here had direct experience on this.

Thanks

[Dave Mcintire]

The thickness of the A model “ways” (the flat part of the bed that the tail stock slides on) is thicker on the A model than on later models. So, regardless of bolt hole location the tail stock will not clamp correctly throughout the length of the bed with the extension. Likewise for the banjo. Thats what I discovered when exploring this.

[Joe Kaufman]

My B "way" thickness is 0.558 inch. Was under the impression that the B was thicker than the A. What is the thickness of your A model?

[Brad Winesett]

Joe - I just measured my 3520A and I get 0.558 inches. So, it is the same as your 3520B.

[Joe Kaufman]

That's good to know. Maybe the thickness change was between the 3520 and the 3520A. I do have the

6294727B bed extension, still in the original box, unused and sits on the shelf between the legs for added ballast.

The hole pattern on the lathe bed is (3) 7/16 dia holes in an inverted triangular pattern. The top pair are 4" center to center and 2 3/4" below the top surface of the bed. The third hole is 4 1/8" centerline to center below the top pair.

[John K Jordan]

The beds on my 3520B and the 18" extension both measure the same, approximately 0.56".

[Brad Winesett]

Joe - I measured my lathe last night and I have the exact same hole pattern as you. One end of my lathe has 7/16" diameter holes and the other has 3/8-16 tapped holes. Both sets have the same pattern. It sure sounds like the "B" extension would bolt right on a 3520A.

I posted this same question in another forum and someone responded that they had to drill new holes to make the "B" extension fit on a 3520A. Could Powermatic have changed the hole pattern on the 3520A at some point?

[Joe Kaufman]

You are correct, one end is taped 3/8-16. I didn't look at that end because of the installed tailstock swing away. The pattern on both legs is tapped holes and there are bosses cast in the legs so there is at least 3/4" of thread engagement. If the cast iron on your legs is only about 3/8" thick in this area, I would think twice about drilling for the lower mounting. Might be better to purchase a new leg.

[JohnC Lucas]

I have a bed extension on my A series and it matches perfectly.