New lathe, need power/motor advice

[jmlcolorado]

I've got a lead on a 1968 Weisser Heilbronn Junior lathe from a neighbor who wants a straight trade for my 1989 camaro RS.
This is no small lathe, weighing in at 3600 lbs.

It has a 7.5hp 3 phase motor. I've been reading up on RPC's and VFD's and with a motor of that size, the cost for either is fairly high.
I REALLY like the added capabilities of a VFD.
Would it be reasonable to change the motor out to a 5hp 3 phase unit and go with a VFD that supports that?

I suppose this is more of a What Would You Do scenario.

 

[Teenager with old tools]

I would say, what do you plan on using it for. Do you plan on using the motor in it as hard as it can be or just light duty


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[J king]

That should work fine unless you want to take heavy cuts like .2 or more per side running carbide

 

[jmlcolorado]

My apologies not not including intended use in the original post.
At this time, I don't really have any specific uses for it, other than getting my feet wet in the art.
I'd likely be starting with turning and threading bungs for exhaust fittings, fuel tanks and so on. Mostly aluminum and mild steel.
I feel like my lack of experience will prohibit me from trying something large right out of the gate.

 

[jmlcolorado]

I presume it would be best to match motor RPM's with the existing motor, correct? Or would having the VFD negate that need?

 

[Ign]

Buy a control box from American Rotary and furnish your own 3ph motor - - - if, of course, you're still open to RPC. It'll be the cheapest option besides building your own RPC from scratch.

 

[larry_g]

Being that is a foreign lathe I would have to ask what the control circuitry looks like? Some of those foreign machines have some creative controls that may or may not support a motor change easily. I would also have you check if that machine will do SAE threads or is it metric only, or do you care? I say this as I have a French milling machine, made for the American market and it has some interesting quirks.

I would also ask, is this machine set up and running in his shop or something he bought and is flipping? Does it have steady rests and tool holders? Do you have someone experienced that can go with you to check it out? It may be a diamond or it may be dirt.

lg
no neat sig line

 

[454ragtop]

Since you're not likely to be pushing the depth of cut to the max, 5 HP should be fine. Actually I bet 2 or 3 HP would be plenty for most home shop types, who cares if you have to take 2 cuts instead of one?

 

[theoldwizard1]

Would it be reasonable to change the motor out to a 5hp 3 phase unit and go with a VFD that supports that?

I would only do it if you are reasonable certain you can SELL the 7.5hp motor. The cost of a 5 hp AND a VFD will kill you. Why do you want a VFD ? Not enough gear box speeds ? A single phase 5hp would be much more economical.

You are also taking a big risk by not seeing it running. Depending on how old and crusty it is, it may need a rebuild, especially if there is a lot of slop/backlash in the mechanisms. Only an EXPERIENCED machinist could tell you that.

 

[jmlcolorado]

Buy a control box from American Rotary and furnish your own 3ph motor - - - if, of course, you're still open to RPC. It'll be the cheapest option besides building your own RPC from scratch.

This might be the route I go.

Being that is a foreign lathe I would have to ask what the control circuitry looks like? Some of those foreign machines have some creative controls that may or may not support a motor change easily. I would also have you check if that machine will do SAE threads or is it metric only, or do you care? I say this as I have a French milling machine, made for the American market and it has some interesting quirks.

I would also ask, is this machine set up and running in his shop or something he bought and is flipping? Does it have steady rests and tool holders? Do you have someone experienced that can go with you to check it out? It may be a diamond or it may be dirt.

lg
no neat sig line

The machine actually has both metric AND SAE on it. It is not running, but he isn't opposed to tracking down a RPC for me to see if go on it's own. He's just flipping it and doesn't have any tooling unfortunately. I know that's where a lot of the klmey will go.

Since you're not likely to be pushing the depth of cut to the max, 5 HP should be fine. Actually I bet 2 or 3 HP would be plenty for most home shop types, who cares if you have to take 2 cuts instead of one?

I'm not oppposed to taking 3, just to get my feet wet.

I would only do it if you are reasonable certain you can SELL the 7.5hp motor. The cost of a 5 hp AND a VFD will kill you. Why do you want a VFD ? Not enough gear box speeds ? A single phase 5hp would be much more economical.

You are also taking a big risk by not seeing it running. Depending on how old and crusty it is, it may need a rebuild, especially if there is a lot of slop/backlash in the mechanisms. Only an EXPERIENCED machinist could tell you that.

I do have a guy I could have look at it with me actually. Thank you for bringing it up!

 

[foghorn1966]

With all the screwing around trying to re-power, move & setup a large untested 48 yr old off brand lathe with no tooling, One must ask how clean is your 89 camaro RS? As the neighbour is flipping the lathe & this deal, he sees way more value in the car. I suspect you are on the downside of this deal.

 

[A_Pmech]

It's my recollection those lathes use the euro equivalent of a C-frame motor. It may be difficult to re-power.

At 7.5 HP, your best bet is a 10HP RPC, especially if you see having other machines in your future.