Powermatic 90 bowl lathe - I want biggerer!

[Lee Alkureishi]

Hi all,

So, I was pretty pleased with the old PM90 restoration, and the addition of riser blocks which brought the wee green beastie up to a 19" swing. After playing with it for a while, though, I kinda sorta wanted something a little bigger, so....

I'm making meself a bowl lathe. Based on a PM90 headstock. It's not quite done, but I'm feeling the need to share it at this stage of development

I wanted to make the whole thing from scratch, using scrap/found metal. And, with the exception of a headstock (purchased for a very reasonable price), tailstock (next to nothing on CL) and short bedways (made by Jeff Nicol, bought from Mike Cruz), I think I accomplished that. Well, I guess it's more of a bowl lathe stand, rather than the lathe itself!

The legs are 2" steel fence posts (1/4" thick), welded together with 1/2" thick angle iron and welded to the underside of 1/2" steel plate. Another 1/2" plate is welded to the top of that at the headstock end, and extends behind the lathe for the motor mount. There's a shelf about 8" below the top plate. The headstock riser is made of the same stuff - 1/4" thick steel fence post columns, welded to angle iron top and bottom, and then clad in 1/8" sheet steel. The top half of the legs is clad at the back and sides in 1/8" thick steel siding. The legs are splayed at 25 degrees, and are 24" apart at the bottom. The legs are also 24" tall, and the headstock riser is 14" tall. With the ways in place, the swing over bed will be 34".

Headstock and tailstock are in the mail! Still have to make a riser for the tailstock, but will need to receive it/measure first. The banjo pictured is a prototype, built for my other pm90. Will need to make a new banjo for this little guy too... For the motor, for now it will get the 1hp 3ph motor I took out of my pm90. But, at Arnfest in September I'll be picking up a nice old 3ph 2hp unisaw motor that should work quite nicely... Planning a jackshaft setup to maintain torque at the lower end.

I learned a lot from this build - namely, how to cut and weld metal(!). Probably should have started on something smaller... I also learned that metal warps (a lot!) when welding... Nothing a little grinding won't fix, but frustrating anyway!

This new beastie is heavy, even before the headstock, tailstock and ballast are added - no idea how much, but I can barely move/drag it. Can't even get close to lifting it. It's sitting on some levelling feet made from 5/8" bolts and hockey pucks. If the lathe rocks/walks with heavy/unbalanced pieces, I'll probably bolt it to the floor.

I'm no mechanical engineer, but I'm hoping the shape/stance of this lathe will be sufficient for its capacity. If not, it'll be hooked up to a VFD, so I can always turn at 4rpm if need be!

[Lee Alkureishi]

Some pics of the build:

[Lee Alkureishi]

More pics:

[Mike Cruz]

OMG! I'm laughing hysterically, here, dude! I can't believe you. You are TOTALLY nuts. I envy the crap out of you, but you are NUTS.

PM90 green, huh? Didn't want to stray and go "different"?

YES, get a VFD. You'll be SO thankful you did. Of course, that means you'll want to make a remote switchbox with all your controls with magnets so you can place it anywhere. You certainly want to be able to put is somewhere to your right so you don't have to reach across a spinning chunk of wood when something is going wrong to slow it down or turn it off. I can send you pics if you want.

When you get your motor, get a 3 hp if you can. A 34" blank may need it. Especially since you might be roughing that puppy at 250 rpm. That means your VFD will be turned way down, which means robbed power. So, as much as reasonable... I've used a bunch of TECO FM50s and have been happy with them. For my last lathe, I got some kind of EBay for cheaper. It has actually worked quite nicely. But it does have a fan that runs all the time. A little annoying unless you are okay with either unplugging it, or putting in a power switch between the VFD and the wall outlet. I'm thinking of installing one of those...

Lee, it is looking great. It really is. I'm very impressed. I'm waiting to see what you do about the speed control dial. Since you won't be needing it, will you just unscrew the handle and let it just stay on there, or are you going to weld up a plate to screw on? Don't forget to leave that accessible for future access to the spindle.

I'm looking forward to the rest of the build. Trudge on, my friend, trudge on.

[Reed Gray]

You did a good job on the base. I am wondering though if you should reconsider the headstock. Mostly, the P90 isn't made (both shaft and bearings) for the big loads you will be putting on it. Might want to step that up as well.

robo hippy

[Mike Cruz]

Reed, I'm not sure about the bearings, because I'm no expert, but that spindle shaft is quite beefy! Now, I don't know what kind of steel it is made of, and what the parameters of the cast iron in the headstock are. But that thing was built back when they made stuff heavier than they needed to. I guess time will tell...

[Lee Alkureishi]

Thanks for the encouragement

Mike - why would I go anything other than my hammered green? I know you did for your behemoth, but I'm a little partial to it, and it'll look nicer next to my pm90 The VFD is a definite (in fact, it'll be plugged into the same VFD my pm90 uses), but I'm planning on keeping the speed dial and reeves mechanism too. I've found I use it more than I thought on the pm90 - it's just nice to quickly change the useable speed range for the vfd's pot. As for the remote switchbox, I already have one! It's not quite as fancy as yours, but it does the job nicely on my pm90's tailstock. I'll need a little ingenious positioning of the new lathe to be able to use it easily on both, but it'll do nicely otherwise...

I would love to get a 3hp motor for this, but the unisaw motor came up on BOYD for $40, so I had to jump! Hoping the older design and 3-phasiness will give it enough torque. I'm also thinking about really jackshafting it down to the low speed range, so that'll increase torque too. We'll see! I did put a switch between my VFD and the wall, for the same reason you stated. It's so nice, just being able to flip the switch instead of having to unplug a twistlock every time.

Robo - thanks for the input about the headstock. I hadn't heard that about the pm90 headstock before - I thought that the spindle size was not far off the 3520's? (1 1/8" vs 1 1/4"). The main negative I've read about the pm90 headstock is that the reeves pulley is located a ways behind the outboard bearing (rather than centered between the bearings), which may not be ideal for heavy outboard turnings.

Either way, it's on its way to me now I'll give it a go, and feed back on my experiences... If it's no good for the big pieces, I'll still have a second, slightly weird looking, and very sturdy pen lathe

Edit: just found out the headstock winging its way to me is pea-green, not hammered green... Ah well, looks like a trip to the paint shop again

[Mike Cruz]

Lee, I can understand the green...no worries. Keeping the color scheme will ad a bit of uniformity to the shop, too.

Glad you are going with the VFD. But not sure about sharing. Not saying you can't, but not sure about it. And if you are, you might want to seriously think about a remote switch (one that is truly remote) that you can bring to whatever machine you are using. You do want those controls close and accessible. Not sure how turning one machine on at a time would work with sharing the VFD...other than having some sort of transfer switch. But then certainly only one machine could be used at a time. Granted it is only you there now, but you might (as I've done) end up with a bunch of turning buddies that meet regularly, and it is nice to be able to have multiple lathes going at once.

Agreed on how nice it is to use the speed control. I found that visitors using the PM90 got easily confused, but I was very used to it.

I didn't realize that you had already bought a motor. That makes sense now... As you likely already know, the Unisaw motor is probably a 3450 rpm motor, so you will most certainly need to match up your pulleys to give you a full torque range of 200 (for when roughing out the really really big blanks) to whatever you want your top speed to be. On my lathe, about 1500 is tops. Personally, for a bowl lathe, I don't think you need to go faster than that...but that is up to you.

Best of luck to you with this build, Lee!

[Richard Coers]

I'm not sure I like the position of the legs. Consider how you stand to work on both sides of the bowl. I like the Oneway because the head is so narrow, and when I need to work around the chuck, I tuck in pretty tight to the lathe, near the headstock. Now consider the length of the chuck with a 10" deep bowl on it. That makes the tailstock leg position a consideration. I would have been tempted to keep the legs on the work side more vertical, but keep the back side legs out like you did. Since you made it though, should be easy to change if you need to.

[Lee Alkureishi]

Hi Richard,

Thanks for the feedback, but I don't think the legs will be a problem. I've played with standing all around the base, and they don't seem to get in the way.

I actually based the set of the legs on the dimensions of the robust american beauty (loosely). They're roughly at the same angle, only the bed is shorter. The lower shelf only comes about halfway forward, and I didn't clad the front of the base. Both of these decisions were made to allow me to stand in closer.

Again, I'm no mechanical engineer, but it seems to me that if the front legs were vertical the whole base would be a lot less stable - the riser + headstock assembly will be a full 20" above the top of the legs!

[Mike Cruz]

Of course, only time will tell with whether or not the legs might be in the way, but for stability purposes, I like them splayed, too, Lee. If the fronts were straight down, I would be concerned that an out of balance 30"+ blank might get the lathe rocking. And if the front legs were straight and it was going to topple over, there is only one way it would go...right at you. So, design wise, I say you did right. Now, again, time (and use) will tell whether they are in the way of your turning...though I think you'll be fine.

[Reed Gray]

As some one who always stands at the tailstock end of the lathe to turn bowls, I am used to straddling the legs. They are always a bit in the way, but it is far easier than bending over, or reaching out away from my body. I do hope the lathe was made to your height. One of the things I love about the Robust is the way the legs telescope out from the body and you can adjust the height. Better than my old PM which I had to put up on a 4 X 4.

robo hippy

[Mike Cruz]

Hehe, Reed, my spindle is a little on the high side for some who visit. I've been tempted to make them a "platform".

[Lee Alkureishi]

Hi Reed,

Like Mike, my pm90 spindle is a little higher than most as a result of the risers - 46" from the ground. That's a pretty comfortable height for me (i'm 6ft), so I designed the bowl lathe to be the same height. Hopefully should be just as comfortable, though I have read that some like their bowl lathes a bit higher than a single lathe.

Like everything else with this lathe - we'll see!

[Lee Alkureishi]

Got a few goodies in the mail today

The speed dial is from my pm90 headstock, which is in a separate package, still to arrive. Looks like the same style as my 1970 beastie.

The tailstock is not a Powermatic - it's actually from a Sebastian metal lathe, but it's easily a match for the pm90 tailstock in heft. #3 Morse taper, but for $25 I can't really complain also has about 6"of quill travel, which is kinda nice...

Lastly, the Reeves pulley is a Powermatic but not from a pm90 - it has a 1" bore. Anyone know of a good'n' cheap supplier of arbor bushings?