Variable speed for a drill press

[McLintock]

I've been reading and re-reading the thread that discusses variable speed for lathes, by either the VFD with 3 phase motor or a DC motor setup. I'm thinking that a VFD and 3 phase motor setup would be good for my 20 year old Craftsman 17 inch drill press with 14X14" table, it's a pretty heavy duty one with 3/4 hp motor. I've also read a pretty good thread on the Practical Machinist site on doing this, but I have a couple of questions they didn't answer. They seemed for the most part to think this was a very worthwhile thing to do.
My question(s) is/are, will a 1 hp VFD and motor supply enough torque at low speeds to do reaming in tough alloy steels, like gun parts. And, if it'll do it, do the 1 hp motors you see on E-bay by Dayton, Baldor and GE to name a few, have essentially the same mounting pattern as my existing motor; they have the same shaft diameter and length? I can't seem to find measurements for the mounting pads anywhere. Mine's about 3" by 5" across for the pad. Y'all seem to know your stuff on this type of thing, so what'cha say; can do or no can do with the 1 hp goodies. Any help much appreciated as I'm not much of an electrician, but I always have been good at adapting stuff.
Thanks,
McLintock

[lathesmith]

McLintock, I doubt you will find a motor with an exact match for mounting in place of your old motor, but you should find one that adapts fairly easily. To answer your torque question, you need to maintain your belt-and-pulley arrangement, even with variable speed. This will give you the ability to "gear down" and maintain the torque you will need for those tough jobs. It would take something like a 5hp motor to give you the same amount of torque and speed range without the pulleys that your current 3/4 hp belt-and-pulley arrangement gives you, and this is just not practical.
lathesmith

[oneokie]

Look on the data plate of your current motor, it should have the frame size listed. Most 3/4 and 1 hp motors are NEMA Frame 56 size. That determines the mounting base dimensions. Also the shaft size and length, keyway size.

Look on the WWGrainger site, they have excellent, IMO, information/diagrams on motor dimensions.

[McLintock]

Thanks guys for the responses, I figured I'd have to keep the stepped pullys and use the lowest speed setup, which is 240 rpm, but since the 3 phase loses power as the frequency and speed goes down, I just didn't know if the 1 hp would do it. Man, a 5 hp would weigh almost as much as the drill press. I figure for tool steel reamers, I'd have to get down to around 60-80 rpm; carbide is the way to go, but they're kind of expensive. You can run them at 200-240 rpm according to my Machinists Handbook. The variable speed drill presses for over $2000 don't go down below 200 rpm, so $250 or so in a VFD and motor isn't too bad a deal.
Enco, in their master catalogue has some specification stuff for electric motors and one listed motor on E-bay had a link to the Grainger site for that motor, and it showed a lot of stuff. I'll check all out some more. I was figuring a size 56 might be the ticket. I'm going to get the stuff and try it, it's only money and it'll keep me out of the bars for a little while.
McLintock

[lathesmith]

If your drill press is anything like my old Delta, adapting a different motor won't be a big deal. Probably your toughest chore will be the pulley to shaft arrangement. I have converted both of my lathes to variable speed, and both required a bushing and milling a new keyway to accomodate the new motor. Or, your current pulley may be too small, in which case lathe boring it would be a simple task.
I used DC motors in my conversions, and on my 13x lathe I replaced a 2 hp AC 1750 RPM motor with a 1750 RPM 2hp DC Baldor. I guarantee you, this replacement Baldor definitely has more torque than the original motor. I would assume that a 3 phase AC setup would work just as well, but I can't say that from personal experience.
Which brings up another important point--be sure your replacement motor is rated for power at a similar RPM as your current motor. If you do this, you will equal or exceed your current setup's power.
lathesmith

[ddeaton]

If you want to insure good torque at low speeds get a good VFD drive. Cheap VFD's run on volts per hertz, meaning to vary the speed you are pulsing the current out to the motor at a given voltage level. More expensive drives have a couple different modes of operation, one of which is called sensorless vector, which means it adjusts the voltage level as the motor is loaded up to keep the speed constant. I have them running on my drill press and Bridgeport. We also have one running on a old 10hp large band saw we use to cut gun stock blanks with. You can only use these single phase on smaller motors up to 3 hp, above that you will need 3 phase. I will post a link to a good source of drives tomorrow, I just got in from a long hockey tourney weekend with the nephews in Detroit and am hitting the hay.

Like the others above stated, look at the frame size on the motor you have. If you stick with the same, all dimensions will match, even the height of the shaft from the mounting plate. By trade I am a controls guy, 30 yrs, dont claim to know it all, but I have been rebuilding machines, mainly large printing presses for that time. There are 500 ways to work up a solution to a electrical project and everyone will have different ideas, not wrong, just different. Any questions you guys have I will be glad to answer. Got to have some disclaimers though, dont want anyone getting hurt.

As Lathesmith stated, DC motors have great torque also. Motors are more expensive new and have brushes, which wear. But for a home shop, probably never wear them out. I will post some links later guys.

[JIMinPHX]

VFDs will give you great range of speed control. They operate in two basic modes, Constant Horse Power & Constant Torque.

When you run the motor at speeds above the nameplate speed on the motor, you are in constant horsepower mode & torque drops off as speed increases. At twice the nameplate RPM, you have half the normal torque of the motor, but that still calculates out to the same horsepower.

When you operate the motor below the nameplate RPM, you are in the constant torque mode. Your torque stays the same as your RPM decreases. When you run at half speed, you are putting put half horsepower, but full normal torque.

It is generally better to gear down & overspeed the motor so that you can stay in constant horsepower mode & use the full available power of the motor. It is quite common to run motors at twice the nameplate RPM. Even at 4 times nameplate, you are not really pushing your luck. The bearings will usually take that without too much trouble. Going slow with the motor (depending on motor type) usually causes overheating problems because a slow turning motor has a slow turning fan on the end of it.

Most VFDs can be controlled by a remote 10k pot (speed knob), remote preset switches, or a keypad on the VFD itself.

Generally, a VFD requires a 3-phase motor, but the smaller ones will usually run off of single phase or three phase primary power. For single phase primary power, you usually need to double the HP rating of the VFD so that you don't blow out the input stage rectifiers. I keep hearing rumors about the existence of a VFD that will run a single phase AC motor, but I haven't seen one yet.

There are all kinds of intricate details that you can get into like carrier frequency adjustments to limit noise, s-curve acceleration for reduced beating on the equipment & junk like that, but for a drill press application, that stuff is kind of a waste.

For applications like yours, I usually build a little control box out of a 4 x 2 outdoor waterproof outlet box & a blank cover plate. If I dig around, I can probably come up with a drawing for the standard switch layout that I normally use.

Regards,
Jim

[McLintock]

Hey, thanks for the great info guys, it'll help a lot, and any drawings, links, whatever will be greatly appreciated. I found a site on the web that takes the mystery of the electric motors, entitled, "The Mystery of Motor Frame Size", and I eliminated several of the motors I was looking at on E-bay right off the bat. It's at http://www.motorsanddrives.com/cowern/motorterms2.html. My only remaining question is, can I use either a ODP or TEFC type motor; the only difference is the TEFC has the enclosed fan on the end.
McLintock

[JIMinPHX]

ODP - open drip proof is just what it sounds like. It can get rained on, but somehow, chips still manage to find their way inside through the open areas. Chips inside = dead motor or dead VFD.

TEFC - totally enclosed fan cooled, is just what it sounds like. The whole thing is enclosed, so chips can't get inside it, but it is still just fan cooled. If you run it slow for long periods of time with a heavy load, it will over heat.

The blower cooled motors are best for low speed operation, but they are very expensive & probably not needed here.

You can make up chip guards for the ODP. You can just run the TEFC at high speeds & gear down when running prolonged heavy cuts. You need to balance your needs against your costs.

[ddeaton]

http://web4.automationdirect.com/adc/Shopping/Catalog/AC_Drives/GS2_(115_-z-_230_-z-_460_-z-_575_VAC_V-z-Hz_Control)/GS2_Drive_Units_(115_-z-_230_-z-_460_-z-_575_VAC)/GS2-11P0

A cheap single phase drive to be used with a 3 phase motor. Will only work in volts per hertz mode in single phase. What I mentioned in my previous post will only work with the 3 phase drive. Are you looking to supply this with 110V or 220V? You will loose torque at low speed, so lean on the large side when picking a motor size(hp). All documentation for this drive and a schematic for hookup are linked on this web page. This is just one brand of many offered, most are a little more $$. I have used this drive quite a bit and the more expensive brands. I would use this again without hesitation.

[JIMinPHX]

http://web4.automationdirect.com/adc/Shopping/Catalog/AC_Drives/GS2_(115_-z-_230_-z-_460_-z-_575_VAC_V-z-Hz_Control)/GS2_Drive_Units_(115_-z-_230_-z-_460_-z-_575_VAC)/GS2-11P0

... I have used this drive quite a bit and the more expensive brands. I would use this again without hesitation.

That should be a good place to get a cheap drive. That outfit used to be called PLC direct. Now that they expanded their product line, they are going by the name automation direct. I never really liked the Koyo PLCs that they sell or the software that went with them, but I have used that place for cheap contactors & things like that before on low end jobs where price point was key. The equipment they delivered was as advertised. I had good results with it.

For a simple application like this, do you think that there is an advantage to using the GS2 series drives over the GS1? I see that the on a 1/4 hp drive the GS2 is about 50% more expensive. I haven't used their drives before so I figured that I would ask. I may be missing some key feature of the GS2 that is needed here.

http://web5.automationdirect.com/adc/Home/Home

It seems tough to get a link for a specific item on that website to work right. The above link takes you to the home page.

[Dutchman]

My question(s) is/are, will a 1 hp VFD and motor supply enough torque at low speeds to do reaming in tough alloy steels, like gun parts.


This 1942 Index mill has a 1/4 hp motor 110v. I've been using it for 25 years just like this for all manner of general milling and drilling up to 1" in steel.

You can get into trouble reading too much about *stuff* on the net.

Remember when automatic transmissions in cars came out? Way cool until you pulled a heavy trailer up a steep hill and that hydramatic became overly dramatic as it got too hot and stopped working altogether. The dude with the 3 speed stick shift just double-clutched and downshifted into 1st gear and kept on truckin' goin' slow and chuggin' up the mountain road. Lathes and mills are alot like that.

http://images19.fotki.com/v33/photos/2/28344/474753/m6-vi.jpg

Real men(tm) use belts and pulleys and the coolest of the cool use leather belts on flat pulleys deciding speeds with ratios of numbers and how much the cutting oil is smoking. No smoke = too slow. A lot of smoke = too fast. I went to college to learn that. There's no smell in the shop better than coal oil while shafts are spinning and belts are slapping in neutral. You can't substitute the excitement of real life by reaching up and turning a dial to speed things up or slow things down.

My god, man, where's your sense of adventure?

http://images111.fotki.com/v732/photos/2/28344/474695/la10-vi.jpg

[ddeaton]

Robert, The only reason I picked the GS2 was the HP rating. I think the G1 will only do .5 HP. No problem at all with the G1 if it falls in specs on what we need. I use their PLCs for the same. Cant hardly buy a solid state timer relay for the price of their small plc. They have good service also, and free shipping over a $300 order. Thanks for the link correction, I always have trouble on here with the links, cant just cut and paste. I need to start using the menu I guess. I love this forum, we have machinists, electrical, casting, shooting resources all in one location and no secrets held back. At least I think.:grin:



That should be a good place to get a cheap drive. That outfit used to be called PLC direct. Now that they expanded their product line, they are going by the name automation direct. I never really liked the Koyo PLCs that they sell or the software that went with them, but I have used that place for cheap contactors & things like that before on low end jobs where price point was key. The equipment they delivered was as advertised. I had good results with it.

For a simple application like this, do you think that there is an advantage to using the GS2 series drives over the GS1? I see that the on a 1/4 hp drive the GS2 is about 50% more expensive. I haven't used their drives before so I figured that I would ask. I may be missing some key feature of the GS2 that is needed here.

http://web5.automationdirect.com/adc/Home/Home

It seems tough to get a link for a specific item on that website to work right. The above link takes you to the home page.

[ddeaton]

Im feeling it brother! I have to admit though, I had a big military lathe like that in my shop for a few years with plans to get it running, I finally gave it away last year, or traded it for white oak to build a boat with. Boat isnt done yet either, thats another forum. A friend of mine hammers out pipe hawks for the reenactors up the road from me. He shows me how to heat treat and anneal from colors, no high teck gizmo's there either.




This 1942 Index mill has a 1/4 hp motor 110v. I've been using it for 25 years just like this for all manner of general milling and drilling up to 1" in steel.

You can get into trouble reading too much about *stuff* on the net.

Remember when automatic transmissions in cars came out? Way cool until you pulled a heavy trailer up a steep hill and that hydramatic became overly dramatic as it got too hot and stopped working altogether. The dude with the 3 speed stick shift just double-clutched and downshifted into 1st gear and kept on truckin' goin' slow and chuggin' up the mountain road. Lathes and mills are alot like that.

http://images19.fotki.com/v33/photos/2/28344/474753/m6-vi.jpg

Real men(tm) use belts and pulleys and the coolest of the cool use leather belts on flat pulleys deciding speeds with ratios of numbers and how much the cutting oil is smoking. No smoke = too slow. A lot of smoke = too fast. I went to college to learn that. There's no smell in the shop better than coal oil while shafts are spinning and belts are slapping in neutral. You can't substitute the excitement of real life by reaching up and turning a dial to speed things up or slow things down.

My god, man, where's your sense of adventure?

http://images111.fotki.com/v732/photos/2/28344/474695/la10-vi.jpg

[Char-Gar]

Dutchman.... I DO like the way you think! I still prefer a brace and bit to an electric drill. Technology went to far the day some idiot put rubber handles on a wheelbarrow.

[JIMinPHX]

Way cool until you pulled a heavy trailer up a steep hill and that hydramatic became overly dramatic

ROFLOL!

You have a way with words sir.

[JIMinPHX]

http://images111.fotki.com/v732/photos/2/28344/474695/la10-vi.jpg

That wouldn't be a Hendy, would it?

[Plumb Center]

I have a VFD with a 3/4hp 1200rpm motor on my 15" Clausing. Seems to work fine for drilling up to 1" holes. A lot of my big bits are WW 2 surplus carbon steel so I have to keep them down to around 80-120 rpm. I like the 1200 rpm motor as I can run it from 600 - 2400 rpm with good power output and get all the speeds I need.
Jim

[McLintock]

Sounds good on that 1200 rpm motor Plumb Center, that broadens the motor availability a little more.
But, I'm locked in now, I just got a Baldor 1 hp, 1725 rpm, ODP, refurbrished motor off E-bay, shipped for $90. It's a 56 frame just like the 3/4 hp motor that I have, so ought to bolt right up. And earlier in the week, I ordered, also off E-bay, a brand new TECO/Westinghouse 1 hP drive for $158, shipped. Now all I have to do is put them together; may be asking a few more questions for that little endeavor. Also looking at a hand held non-contract tachometer for measuring rpm at the chuck, so I know when I'm at the right rpm.
Thanks again for all the help and stuff.
McLintock

[JIMinPHX]

Also looking at a hand held non-contract tachometer for measuring rpm at the chuck, so I know when I'm at the right rpm.


I've rigged up a few lathes with a prox switch that looks for a Allen head that I tapped into the back of the spindle. I then feed the prox switch signal into a counter & bingo - instant tach, permanently mounted on the headstock of the machine.

[JIMinPHX]

Most of the time when I set up a manual mill, or similar machine with a VFD, I usually mount a small control box at the operator station & put the drive itself far from harm's reach. I make the control box out of a 4 x 2 waterproof outdoor electric box that is available at Home Depot. I drill out a blank face plate to accept standard sub miniature switches that you can get at Radio Shack & a standard potentiometer. I use a red 16mm pushbutton for the stop switch. The extra toggle switches let you have preset speeds that you can go to automatically with the flip of a switch. You can also just use the dial to get any speed you want. There are two layouts that I normally use. One has presets. The other doesn't.

[McLintock]

Thanks Jim, that'll be a great big help.
McLintock

[Buckshot]

Sounds good on that 1200 rpm motor Plumb Center, that broadens the motor availability a little more.
But, I'm locked in now, I just got a Baldor 1 hp, 1725 rpm, ODP, refurbrished motor off E-bay, shipped for $90. It's a 56 frame just like the 3/4 hp motor that I have, so ought to bolt right up. And earlier in the week, I ordered, also off E-bay, a brand new TECO/Westinghouse 1 hP drive for $158, shipped. Now all I have to do is put them together; may be asking a few more questions for that little endeavor. Also looking at a hand held non-contract tachometer for measuring rpm at the chuck, so I know when I'm at the right rpm.
Thanks again for all the help and stuff.
McLintock

..............I put a Teco/Westinghouse VFD on my mill.

http://www.fototime.com/C12AB0477A094C7/standard.jpg

You'll probably fare better then I did as the instructons are written for people who already know about them and have experience. I didn't and was totally at sea, and I was afraid to hook up power for fear of having it simply explode :-) The customer service people at Teco/Westinghouse were first class all the way.

The one for my mill is a 3 hp unit and I don't know about model similarities, but one of the (many!) confusing deals in the manual was (I found out later) their referenceing the unit's ability to be operated remotely (those small connections low on the face).

FoR a hand held non-contact tach, check out the unit Harbor Fright sells. I bought one to reference mill spindle speeds to know what freq's resulted in what rpms. Works a treat!

.................Buckshot

[JIMinPHX]

I was afraid to hook up power for fear of having it simply explode :-)

If you put power to the motor connections, that is exactly what will happen. The output thyristors go off like M-80s.

[McLintock]

You guys are starting to make me nervous, as I'm about in the same boat as you were, Buckshot. Both of you, please stand by.
McLintock

[Buckshot]

You guys are starting to make me nervous, as I'm about in the same boat as you were, Buckshot. Both of you, please stand by.
McLintock

..............If you have a question or problem call their customer service folks. As I said, they were tops, and knowing I was an idiot dealing with the VFD they didnt treat me like one :-)

..............Buckshot

[Dutchman]

That wouldn't be a Hendy, would it?

Negatory.

Von Wyck - Cincinnati, Ohio. Used primarily in the automotive industry. This lathe was made just about in the narrow time frame of 1903-1905. We know this because of the name plate, mostly. The company was known as Roach & Von Wyck up to 1903 then just Von Wyck. The name plate on mine has something that was scapped off in front of the Von Wyck which I surmised was "Roach". I have a photo of a later name plate that is identical to mine except there was nothing in front of Von Wyck leading one to assume it was made after the consolidation of the business and Mr.Roach went his merry way. In 1905 they went to a quick change gear box. Mine is of the archaic change gear method of threading.

Dutch

[JIMinPHX]

Negatory.

Von Wyck - Cincinnati, Ohio. Used primarily in the automotive industry. This lathe was made just about in the narrow time frame of 1903-1905. We know this because of the name plate, mostly. The company was known as Roach & Von Wyck up to 1903 then just Von Wyck. The name plate on mine has something that was scapped off in front of the Von Wyck which I surmised was "Roach". I have a photo of a later name plate that is identical to mine except there was nothing in front of Von Wyck leading one to assume it was made after the consolidation of the business and Mr.Roach went his merry way. In 1905 they went to a quick change gear box. Mine is of the archaic change gear method of threading.

Dutch

I used to have a Hendy that looked almost exactly like that, except it had a quick change gear box. It was the same color as your tail stock. She was one rigid unit. I "replaced" her with a Clausing Colechester. That Clausing is a nice little lathe & all, but I miss the beef of the Hendy when I try to take heavy cuts.

[JIMinPHX]

You guys are starting to make me nervous, as I'm about in the same boat as you were, Buckshot. Both of you, please stand by.
McLintock

Relax, we're here for you. Just keep posting your questions & make sure that you don't get the power leads confused with any of the others, including the motor leads.

I've done about a million of these things. I designed & built my first one from scratch back in the late 80's, back before they were an off the shelf item. I've done board level repairs on drives that other people have built without even having the benefit of a schematic drawing before too.

You will get through this. It's not going to be that bad. The modern drives are pretty user friendly, you just need to figure out a few little idiosyncrasies for the particular one you have & not carelessly misplace a wire.

I only posted the caution about not confusing the power & motor leads because that was one of the classic mistakes that old timer elevator mechanics used to make when troubleshooting VFD based controllers for the first time. They would jump out the drive as if it was a contactor to see if the motor would spin & BANG, little chunks of plastic & shrapnel would come blasting out the side of the VFD case. On a 25hp drive, that can be a fairly dramatic event. Some of those elevator guys actually had the balls to try to return the drives they blew up under warranty. Unless they had a lot of clout (like they bought 100+ drives per year), that one didn't fly.

[JIMinPHX]

McLintoc, are you still there?

[McLintock]

Hi Jim,
Yes, I just replied to your e-mail, but will give a wrap up here in case anyone's still interested. I got it working, but not without some head scratching. The VFD directions said to connect it's terminals to the lettered wires or terminals on the motor, but the motor only had 9 numbered wires coming out of it. I finally found a site on the internet with a forum that discussed that very thing and got the proper connections (I had it wrong of course). Then, after popping the GFI outlet several times, I hooked it up to a non GFI outlet and figured out that GFI outlets weren't the way to go. Switched out to a normal outlet and everything works now. Just got a non contact tach in the mail yesterday (the Harbor Freight one wasn't in stock in the store I visited in the Phoenix area), so I'm ready to go. I wired it up to use the original on/off switch on the drill press to turn the VFD on and off, and in that hook up I can still use the light on the drill press for a work light. The motor went right on the drill press and lined up perfectly so no problems there.
All is well for now.
Thanks for the help and ideas,
McLintock