New (used) lathe ...

[precisionworks]

I don't feel the wiring will be a challenge

I'll PayPal gas money to get to The Heartland & you can redo mine :nana:

My machine has an access door interlock, foot brake interface, jog switch, coolant pump that needs to run at full speed regardless of motor speed, E-stop, plus the "normal" Run/Stop/Reverse switches. It would take me longer to figure this out than to build the RPC.

your's would work but I don't think it would fit down my stairs

Moving 3000# of iron on smooth concrete was a challenge - moving that same load down a flight of stairs would be a bear. The machine could be broken down, but I'd guess that the stripped base would go over 1000#, probably closer to 1500#.

 

[wquiles]

My machine has an access door interlock, foot brake interface, jog switch, coolant pump that needs to run at full speed regardless of motor speed, E-stop, plus the "normal" Run/Stop/Reverse switches. It would take me longer to figure this out than to build the RPC.

Yup, same for my lathe:

Door interlock - check!
Foot Brake interlock - check!
Jog Switch - check!
Coolant Pump - already disconnected completely!
Run/Stop/Reverse and E-switches - check!

I am more than fully aware that you are running your shop as a business, so in your case "time is money". As you know for me this is still a hobby, so having the machine out of commission for a couple of days or two weeks is nothing to me. Doing the VFD conversion on the lathe will be just another great learning project - after all, it is "your" fault that I am now looking at my 3rd 3-pahse VFD project :devil:

 

[precisionworks]

it is "your" fault that I am now looking at my 3rd 3-pahse VFD project

I'm considering VFD #5 (for the mill) but still have a few tooling expenses left for the bigger lathe :D

 

[precisionworks]

Finally :D

A stand was welded from 2"x2" angle, with two pieces of 3/4" plywood glued & screwed together, then covered by a tempered Masonite top. A shelf support was welded in so a plywood shelf can be installed.

The RPC rests on a sheet of rubber gasket material that is stapled to the Masonite. U-bolts hold the motor to the top.

The rubber pad keeps the motor slightly dampened, and the U-bolts each have a rubber sleeve to avoid metal to metal contact.

The disconnect wiring is pretty straight forward.

Turned on the pony motor, brought the idler to full speed, threw the disconnet handle to the ON position & the big motor never missed a beat. Zero starting surge, no light dimming at all. The pony is then turned off & the belt is flipped off the pony. The big idler is as quiet as any commercial RPC I've ever used - from about 6' away, only fan noise can be heard.

Set the lathe to for 1000 rpm & pulled the red handle up - she came to full speed in an instant :D Same result at 1450 & 2000 rpm, although 2000 rpm sounds like an F-16 on 'burner. Ran through all the lower gears as well, and engaged the compound feeds in different positions. I wire up quite a few 3ph motors at work, plus a few more in my shop, and the odds of correct motor rotation are 50-50 (meaning that two leads have to be swapped to reverse rotation). For whatever reason, this one rotated in the correct direction :crackup:

No chips yet, as the T-nut has to be machined ... hopefully Friday or Saturday.

Here's a photo from the PM forum on a really neat design. To quote the builder "Foot pedal engages friction clutch, gravity disengages." I was going to use this design but could not find the photo until today:

 

[Torque1st]

AFAIK -If your pony motor is not a capacitor run motor I believe you can safely couple it permanently to your idler. It just provides additional inertial mass at that point.

Then you can put a belt guard over the unit before it grabs a shop rag or apron.

 

[precisionworks]

You're right, the pony could be set up as a "normal" belt drive with tensioned belt & belt guard, but there are some reasons not to do that. Even switched off but still belted, the pony fan makes almost as much noise as the idler, and the combination is loud. Parasitic drag from the pony is another issue, as is bearing wear (although that would be tiny).

Not sure that I was clear on the start up procedure, but the pony is first switched on & then lifted back on the hinges so the belt is tensioned. The disconnect is thrown to the ON position & the pony is turned off & returned to the "resting" position. The slack belt, being driven now by the idler, flips itself off the sheaves & rolls over to the door, leaving nothing to catch on except the smooth sheave on the idler. Since no one is ever in the shop when the lathe is being used, it should not be a concern.

It would be different if there were any employees, but there have never been (nor will there ever be) anyone on the payroll. OSHA is a non issue as long as there are no employees.

 

[StrikerDown]

Is that true 3 phase going to the lathe?

I don't understand how you can get there with L1 and L2 being tied directly to the T1 and T2. It seems like they,T1 and T2 would retain the 180 degree phase relationship of L1 and L2 and T3 would fall somewhere in between.

Obviously it works! I'm just confused never having seen this set up before! :shakehead

Edit:

Google is a wonderful thing:

http://www.paragoncode.com/shop/rotary_converter/

Looks like this provides unbalanced 3 phase. Works fine where you don't need balanced 3 ph, it's just a little different than the usual 3 ph found in commercial applications.

 

[Torque1st]

You're right, the pony could be set up as a "normal" belt drive with tensioned belt & belt guard, but there are some reasons not to do that. Even switched off but still belted, the pony fan makes almost as much noise as the idler, and the combination is loud. Parasitic drag from the pony is another issue, as is bearing wear (although that would be tiny).

Not sure that I was clear on the start up procedure, but the pony is first switched on & then lifted back on the hinges so the belt is tensioned. The disconnect is thrown to the ON position & the pony is turned off & returned to the "resting" position. The slack belt, being driven now by the idler, flips itself off the sheaves & rolls over to the door, leaving nothing to catch on except the smooth sheave on the idler. Since no one is ever in the shop when the lathe is being used, it should not be a concern.

I understand how it works. I have seen the application a number of times.

Since the pony is only intermittent duty the fan can be removed so that is a non-issue.

Chasing the belt across the room and having to pick it up and store it etc would be an irritation to me. But that is just me.

The pony motor bearings would be a tiny drag but the belt hysteresis losses would be a greater loss. It is insignificant in the application tho. My build uses a coupling instead.

You may be surprised what that "smooth" sheave on the idler can catch. Especially if for some reason a person stumbled against it. I worry about my personal safety.

 

[precisionworks]

Looks like this provides unbalanced 3 phase.

Without balancing caps, the outputs are unequal. T1 & T2 read 125v (to ground) while T3, the manufactured leg, reads 170v, pretty typical of any RPC that has no balance caps. It's easy enough to add balance caps & get all three voltages within a few volts of each other, and that does generate less motor heating, but 3ph motors could care less what they are fed - think of a 3ph motor as a large rotating inductor. Feed it some approximation of 3ph and they start fast & run with the the same power & torque output that commercially generated 3ph provides.

Works fine where you don't need balanced 3 ph

CNC controls are the one area that requires utility quality power. Neither an RPC or a VFD provide this. The VFD output has 3 phases that are 120 degrees out of sequence from each other, with equal voltage, but VFD waveform is far from sinusoidal:

That's the college textbook version, which isn't too ugly. Hook a scope to a freq drive & you'll see this:

There are, at present, just three ways to obtain commercial quality 3ph. First is to buy it from your utility - which would have cost me $5k in 2003, probably closer to $10k today. Second is to purchase a 3ph generator - a small 10 kw unit (20 hp gas engine drive) is about $5k today. Third is to purchase a digital phase converter like a Phase Perfect - $3k for a 10 hp unit.

Or build a RPC for a hundred bucks :nana:

You may be surprised what that "smooth" sheave on the idler can catch.

You're right, it does present some hazard. I'll see if I can come up with a quick detach cover, which shouldn't be too hard.

Chasing the belt across the room ...

It stops as soon as it hits the overhead door, about 36" away. Surprisingly, the pony was set for CCW rotation for just that reason :D

 

[KC2IXE]

MOST VFDs provide non sinusoidal

Back in the 1980s/early 1990s I worked for an electonics company that made some VFDs - if you had one of theres, you wouldn't be worried at all - you could switch the load on and off without blowing the VFD, it could handle -90 to +90 loads (aka everything from pure capacitive to pure inductive loads), and had a THD on the sine wave that requires some pretty fancy gear to measure (like .001 THD and less)

Of course, back then, it had a high 6 digit price tag, but what the military wanted, the military got

 

[precisionworks]

Started today by jacking up the lathe to install the Mason mounts. Wrench the left jackscrews all the way down, place as much packing as possible under the mid jackscrews & wrench those down, etc. Just needed to raise the base 2", as that's the minimum height of the Mason mount plus hardware:

Once the base was up, a 2"x4" steel block was placed under both corners. The jackscrews by themselves would probably hold up the base, but I wouldn't put my hand under the base without the 2x4 blocks.

The tail stock end was lots easier ... position the 60" pinch bar under the end, press down, up comes the base. My knee held the pinch bar in position while the 2x4 blocks were slid under the base:

After all six mounts were installed, the lathe was precision leveled. Mounted a 2" diameter piece of 1144 Stressproof in the 3 jaw and took a very light cut over a six inch section. Both ends measured within .0002" of each other, so no head stock adjustment was needed.

 

[wquiles]

Alright !!!

Cutting chips :party: :party: :party:

 

[precisionworks]

Only one issue so far - the machine came with a 3-jaw chuck (6") and a 4-jaw chuck (8") that have through holes smaller than the head stock bore :sick2:

With the D1-5 mount, it's easy to find a 3-jaw 8" and a 4-jaw 10". The 8" chuck has a 2.15" hole, while the 10" opening is 2.55". EBay yielded a nice looking 4-jaw (Bison 7-853-1035). Cost was well under half of the best new price on the web. There are lots of 8" 3-jaws on eBay, but I decided to step up to the plate & get a nice one - Bison 7-866-0800 - Set-Tru, forged steel (not cast iron like the 10") with two piece jaws. Got the lowest price from my friend Rocky at Ajax Industries. Had a balance in my PayPal account that helped cover the $1200 for the two ($330 + $870). Both current chucks will go on eBay which will reduce the cost of the new ones.

And I still have to buy a few tool holders :oops:
For the CNMG-43x insert, the most popular tool holder is the MCLNR. I found a neat one made by LMT Fette at industryrecycles.com. Coolant through (Fette calls it Direct Flow) so the coolant hits the cutting edge. The holder plus 10 inserts was $58 delivered, about $20 cheaper than the same item from their eBay store :wtf:

 

[wquiles]

There are lots of 8" 3-jaws on eBay, but I decided to step up to the plate & get a nice one - Bison 7-866-0800 - Set-Tru, forged steel

Money well spent. I still say that although a lot of money, they pay back due to how simple and how much less time it takes to do precession work (hey, isn't that your user name? :devil: ). I don't even know when it was the last time I had to center anything on my Bison Set-Tru. Once aligned (mine is set to less than 0.0005"), you basically forget about it. Even when swapping parts around, the center is so close that you have to run your thumbnail to detect the slight difference. And if you mark your piece (say aligned with the "0" in the chuck), when when you remove the piece to measure and later re-chuck it aligned with your mark, you are back "spot on" where you were - simply amazing :thumbsup:

 

[precisionworks]

You probably guessed that the 6-jaw Set-Tru was also on the wish list ... but a heart transplant costs less :D

 

[darkzero]

Money well spent.

I don't even know when it was the last time I had to center anything on my Bison Set-Tru. Once aligned (mine is set to less than 0.0005"), you basically forget about it.

Awesome, I agree with Will. :thumbsup:

On top of that, I've removed the Bison chuck a few times to use the other chucks & to my surprise after put the Bison back on, run out is exactly what is was before taking it off. Of course I have marks on the spindle & backplate to reinstall it in the same position. I thought for sure I would have to make some minor adjustments when reinstalling the Bison.

Got the lowest price from my friend Rocky at Ajax Industries. Had a balance in my PayPal account that helped cover the $1200 for the two ($330 + $870).

Very cool. Although not the great price Will & Brian paid back then, I also got my Bison 6 jaw Set Tru from Ajax Industries. Paid $960 shipped from Toolmex including the Bison adapter. They had the same deal for the 8" 6 jaw for $1200. They always seem to have the best deals. :twothumbs

 

[wquiles]

For the CNMG-43x insert, the most popular tool holder is the MCLNR. I found a neat one made by LMT Fette at industryrecycles.com. Coolant through (Fette calls it Direct Flow) so the coolant hits the cutting edge. The holder plus 10 inserts was $58 delivered, about $20 cheaper than the same item from their eBay store :wtf:

That is the same exact one that you modded for me - still using it today as my workhorse metal remover, and so far with the Al-specifc inserts this holder gives me the best finish on Al and on Copper :thumbsup:

 

[precisionworks]

I also got my Bison 6 jaw Set Tru from Ajax Industries.

+1

I always speak with Rocky, who really tries to give their lowest price. By going direct to the distributor, no eBay fees are taken out of their payment and the item costs less. The Bison items have gone up in price as more people realize the very high level of quality. My new Set-Tru cost little more than any number of used chucks (Buck, Cushman, etc.).

Also, if you search eBay through Bing.com, there's as much as an 8% discount on Buy-It-Now items. I thought about this two days after buying both chucks :(

 

[precisionworks]

The Brown Truck left two packages yesterday, both from Bison/TMX :D

Machine work on the parts is superb ... both sides of the back plate have been Blanchard ground (by a rotary surface grinder) so that both sides are dead flat & perfectly parallel. The back surface of the chuck received the same treatment. Since my spindle nose is also Blanchard ground, there should be nearly zero axial run out ... although the indicator showed .0001"

Close up view of the back plate:

Before mounting the back plate to the spindle nose, I pulled all the locking cams for cleaning, deburring, and greasing. No sense taking a chance on a leftover piece of grit scoring one of the new locking studs. Two of the studs had to be backed out one turn for proper cam engagement, but nothing else. A piece of Thomson linear shafting was used to dial in the radial run out ... about .0002" to .0003" TIR - well under the .0004" that Bison guarantees :D

I rechucked the 2" bar of 1144 Stressproof and took a couple of very light cuts with the end unsupported. The DCGT-32.50.5 from Rani Tool was used for this test as it is super sharp. Where the diameters had showed .0002" difference before, the DCGT left a surface that had only .0001" (or a little less) difference from end to end.

Even with a decent sized part in the chuck, there's still room for more:

On edit 04-19-2010 - the 4-jaw Bison came on the Brown Truck ... the driver seems a little weary these days ...

Those are the photos from the eBay listing so they lack some detail, but the chuck has almost zero wear. Purchased from Rochester Machinery Suppliers http://stores.ebay.com/ROCHESTER-MACHINERY-SUPPLIERS-INC

I phoned last week & spoke with a guy named John - who owns the business. The UPS calculator on eBay showed $88, which he said was way more than it should have calculated. I had John ship & bill to my UPS account & the cost was $26.27. The chuck arrived in a custom built plywood box, 3/4" thick, screwed together on all sides & strapped with steel banding - my kind of shipper. A superb company & person to deal with :)

 

[Mettee]

....man that looks nice I am envious. That is the set up, or the type of set up I want at home. Soon I hope.