Converting Drill Press to Variable Speed

[bmwman91]

I think you made a good choice going this route. i am kinda surprised that you purchased the parts off ebay when they are so readily availible to you locally.

https://sfbay.craigslist.org/scz/spo/d/capitola-live-strong-treadmill/6935428322.html

https://sfbay.craigslist.org/pen/zip/d/south-san-francisco-livestrong-ls130t/6935314644.html

https://sfbay.craigslist.org/eby/for/d/fremont-vitamaster-triumph-by/6934989502.html

https://sfbay.craigslist.org/sby/spo/d/san-jose-ironman-treadmill/6928302480.html

https://sfbay.craigslist.org/eby/spo/d/danville-free-treadmill-nordic-track/6934834173.html

https://sfbay.craigslist.org/nby/spo/d/geyserville-golds-gym-treadmill/6934758782.html

https://sfbay.craigslist.org/eby/spo/d/dublin-treadmill/6934063194.html

Andrew: to be clear, i used a 1/7hp motor on my mini lathe. bmwman is correct. treadmills have motors that are in excess of 1 horsepower but the comparison to an induction motor is not equal. the DC version makes so much more torque. this is why they are used in treadmill applications in the first place. think of some 400 lb fat fucker jumping on that thing trying to walk up a 6 degree incline.....

You are correct that I could DIY part-out a treadmill. There is a reason why entire treadmills are so cheap. It would cost north of $200 to have junk haulers take it out of your house. I don't need a half-disassembled treadmill on my property...I have already spent a lot of money to de-junk my house over the last few years!

Also, the eBay seller apparently dropped the box on the way to FedEx and broke the controller or something. I have asked them to cancel the order, so I will keep an eye out for other setups. At the same time, I am still thinking about the $$$ BLDC setup since the controllers have braking functionality, reversing for occasions when I need to extract broken shit, closed loop speed control, and the external PSU can run on 240V input which would allow me to keep the $30 NEMA twist lock plug on the cord I made for the drill press (despite the BLDC setup costing way more than $30).

Anyway, I am still looking to see if any good treadmill setups are around online.

[flyboyx]

in my area, i could just set the detrius out by the street and some metal scrap hauler would make it disappear in less than 3 hours.

all of the features you are looking for are availible for brushed permenant magnet motors. the DC control box i have on my little lathe in the video i posted above has brake functionality. watch the video again and take a good look at the controls on the box. i didn't bother hooking it up. i couldn't imagine a good use for this feature on my drill press. since you switched over to a hand tightened chuck, i guess i could see how it might come in handy for you. personally, i am going to stay with a keyed chuck for my drill press. in my experience, i don't think the convienience of hand tightening offsets the greater tightening ability(leverage) a traditional chuck provides.

an option for you in liu of a braking feature would be to add something to the spindle pulley on the top of your machine that you can easily lock in place or perhaps some sort of handle you can hold with one hand while tightening the chuck with your other hand.

as to reverse, the motor is DC. all you have to do is swap the power leads to the motor and it will run backwards. a simple separate switch would take care of that just fine.


the twist lock plug is a really cool feature, but you do realize you are going to spend another 300 bucks in order to save 30?

i understand that you are probably looking at this project as a forever tool. there is someting to be said about cool projects that don't make economic sense. i'm pretty sure you are going to have over 600.00 invested in this tool if you decide to use something other than a tread motor. that is easily 2x the value you would ever hope to recoup.

[Exodus_2pt0]

Useless post, but I didn't there was such a thing as a brushless dc motor. I thought all brushless motors were AC, and the speed controller converted it to ac.

Learn something new every day.

[ForcedFirebird]

Nice job!

I inherited a Delta 17-900 of about the same vintage from my woodworking neighbor. How did you find out what year it was made? I see yours is also Taiwanese.

I like the old vintage machinery, also have 1987 Ohio Forge 510-440 table top DP, 1955 Delta Toolmaker, a 70's Sioux Valve grinding station, 1983 Miller Syncrowave etc...

[bmwman91]

in my area, i could just set the detrius out by the street and some metal scrap hauler would make it disappear in less than 3 hours.

all of the features you are looking for are availible for brushed permenant magnet motors. the DC control box i have on my little lathe in the video i posted above has brake functionality. watch the video again and take a good look at the controls on the box. i didn't bother hooking it up. i couldn't imagine a good use for this feature on my drill press. since you switched over to a hand tightened chuck, i guess i could see how it might come in handy for you. personally, i am going to stay with a keyed chuck for my drill press. in my experience, i don't think the convienience of hand tightening offsets the greater tightening ability(leverage) a traditional chuck provides.

an option for you in liu of a braking feature would be to add something to the spindle pulley on the top of your machine that you can easily lock in place or perhaps some sort of handle you can hold with one hand while tightening the chuck with your other hand.

as to reverse, the motor is DC. all you have to do is swap the power leads to the motor and it will run backwards. a simple separate switch would take care of that just fine.


the twist lock plug is a really cool feature, but you do realize you are going to spend another 300 bucks in order to save 30?

i understand that you are probably looking at this project as a forever tool. there is someting to be said about cool projects that don't make economic sense. i'm pretty sure you are going to have over 600.00 invested in this tool if you decide to use something other than a tread motor. that is easily 2x the value you would ever hope to recoup.

You are correct that this is mostly a "cool factor" project, and I am 100% unconcerned about future resale value or recouping costs. I am already more than the original cost/value of this thing into it from the rebuild and keyless chuck. I still have the keyed chuck for it for the times when I am dealing with high torque operations like large hole saws and drilling steel plate, but the keyless is just fine and super fast for the other 90% of the stuff I do on it.

Braking functionality is mostly for frequent start-stop operations when I need to reposition a workpiece (or swap them) many times and don't want to do it with a 2" Forstner bit rotating near my fingers. I also often am in a situation where I need to do multiple holes in a part, starting with a pilot hole, then the actual hole and then countersink and/or tap it. To maintain concentricity, it is best done one hole at a time, swapping bits, and waiting for the spindle to stop on its own takes forever.

Useless post, but I didn't there was such a thing as a brushless dc motor. I thought all brushless motors were AC, and the speed controller converted it to ac.

Learn something new every day.

Yup! They are not actually DC motors in any similar sense as a brushed motor, except that the main power supply is DC. The controllers modulate the DC voltage into 3 phase trapezoidal or sinusoidal signals. The motor's stator windings interact with permanent magnets on the rotor to spin it.

Nice job!

I inherited a Delta 17-900 of about the same vintage from my woodworking neighbor. How did you find out what year it was made? I see yours is also Taiwanese.

I like the old vintage machinery, also have 1987 Ohio Forge 510-440 table top DP, 1955 Delta Toolmaker, a 70's Sioux Valve grinding station, 1983 Miller Syncrowave etc...

I am just guessing on the year based on the manuals for it I found online. I do sort of like some of the older woodworking tools more than the newer ones since they seem to have a lot more cast iron in them.

[bmwman91]

OK, attempt #2 to do this with a treadmill motor on the cheap'ish. Back when I researched this a bunch a year or so ago, I found that KB / Nidec make decent DC motor drives which are reasonably priced on eBay. My inclination was to go with a KBPW-240D which is one of their PWM drives, but it has some power limitations with 90-130VDC motors and a couple of other missing features. So I went with the KBPC-225D SCR drive which has speed- and torque-control drive modes and can handle a lot more output current. All in all, this ran me $5 more than the first all-treadmill-parts eBay item which fell through, and in this case I have basically everything I need to run this out of the box. I can even maintain my 240V input too and just set the drive's MAX trimpot to not go much over 130VDC. As far as I can tell, it does NOT include dynamic braking functionality, which is something like $100 worth of accessory add-ons. I may just come up with a mechanical brake system since I will be machining custom pulleys and motor adapter brackets.

Other than that, I am still planning on making a microcontroller-based tach with some big 7-segment LED blocks.

https://www.ebay.com/itm/KB-ELECTRONICS-KBPC-225-KBPC225-NEW-IN-BOX/233290854397

https://www.ebay.com/itm/Used-Permanent-Magnet-Treadmill-Motor-Hobby-Variable-Speed/173955411743

[flyboyx]

That’s really cool man. So that controller was around 200 bucks? Not cheap, but I think it will serve you well. I found my lathe controller on eBay too. Apparently the guy selling it found it at an estate sale. I bought it used, but it had never been installed before. The specs say it’s made for 1/8 to 1 hp. Apparently 45.00 shipped was a pretty good deal.

I am thinking about a way to make it modular so I can run my 1960’s craftsman press with it too. I guess I won’t find another that cheap.


I see there is a spot on the panel for brake. It’s a shame you don’t have that feature in your price point.

[bmwman91]

Yeah $155 shipped seemed pretty good for new commercial-grade DC motor drive box. Agreed, it is too bad that none of them come with the brake accessory, but I will keep an eye out for a deal on one. Chances are that once I put in pulleys with a LOT less mass, the spindle will come to a stop much more quickly. The stock main spindle pulley has to be north of 5lbs, and close to 10" in diameter at its largest. It probably helps to smooth the operation a little, similar to a flywheel in a car.


We'll see how it does. It is an SCR-type drive, so there is the inherent RFI that will be generated, and the motor will be a bit noisier with the 120Hz fundamental harmonic from the chopping action. I am still hopeful that it will run quieter than the TEFC induction motor that is on there now.

[bmwman91]

OK, so does anyone on here want to buy the DC motor control and 2 working DC motors from me?

- The first one which I got on eBay had a worn bearing, so I am replacing both of them. The new bearings are high quality NTN double-sealed ones from Motion Industries, which I should have in a week or so.

- I then bought a second one (see Surplus Center link) which is "new". I disassembled it to get some measurements on it (too large a diameter for even my 12" caliper jaws) and found that one of the internal permanent magnets was cracked. I pulled out the small loose piece, and there are some larger bits which appear to still be glued into place. Once I got the chipped bits out and reassembled, it runs fine and does not make crunching noises or anything...seems to be fine.

https://www.surpluscenter.com/Electrical/DC-Motors/Special-Purpose-DC-Motors/3-HP-Icon-Treadmill-Motor-Without-External-Fan-F-309513-ZDY116-MNT-081-10-3048-A.axd

- The motor control is brand new and in immaculate condition. Apparently this model does not have a braking module accessory option. That alone wouldn't be a deal breaker on the whole project, but the motors I bought irk me.

Anyway, both of the DC motors are about as loud as the AC induction motor on the press now, and my OCD is triggered by these surplus goods lol. I'll sell all 3 items for $200 shipped (everything, including nice new ball bearings, were $330 with shipping when I got them). Let me know if you are interested before I plop it all on Craigslist.




So, WAT DO NOW? BLDC motor conversion, that is what. Yes, I have just wasted a really good bottle of Scotch's worth of money figuring out how I don't want to do this. Also, yes, the BLDC parts are another chunk of mostly-unnecessary change. Compared to what I, and many of us here, have done with our 30 year old cars, I feel no guilt. YOLO

[bmwman91]

OK, the conversion is well under way now. Here's the deal.

First, I made some accurate-enough CAD models of the drill press head, pulleys, motor and PSU. After much noodling about where to put the PSU, I decided that it would be best to locate it inside the belt housing. It has some very high-flowing fans, which are loud and will suck sawdust, so the belt housing will help a little. Since this thing will not operate in any sort of continuous fashion, thermals are not much of a concern.



Things are a little tight, no? A number of modifications were needed to the drill press:
1) The step pulley on the spindle would need the 3 unused sections removed



2) The top "deck" of the head casting would need to be lowered a few millimeters to give the PSU adequate clearance under the V-belt. With no changes, there is a ~3.5mm gap. I'd prefer to have a bit more room, like 7mm just to make sure no accidental contact occurs.



3) The motor mount bracket has always vibrated a lot since it is basically a big cantilever. To eliminate this, I will have a long M8 threaded rod and some nuts rigidly secure its bottom to the head casting. Since I am eliminating the step pulleys, this poses no inconvenience.



The new motor will be held by some machined aluminum collars, all mounted to an aluminum back plate.



Getting the new pulley onto the motor will take most of the work. The existing shaft will have some JB Weld fill in the flat sections (not structural, but will give a little more bearing surface), and then sections of it will be turned down a little to clean things up. It's machine pretty poorly from the factory. Also, the 6001 sealed bearings are cheap as hell and I am replacing them with some nice SKF ones.



The adapter will be locked to the shaft with a 3/16" machine key, and then the pulley will use a 1/4" key. McMaster sells shaft stock with external keyways already machined into them, so I only need to turn the inner features, part it and broach the 3/16" keyway.





I had my concerns about the bending stresses that would be generated with this setup since the V-belt is pretty far off from the front bearing, and the shaft is not very large. Using some very conservative worst-case assumptions, I found that I still had a safety factor of >3, so the shaft should hold up just fine.





So, lots of CAD and Excel stuff. Cool story bro?

Nah, after getting the general design idea settled, it was time to start doing stuff.

The step pulley was parted down. Not only did it give my PSU the horizontal clearance I wanted, but it also SIGNIFICANTLY reduces the rotating mass of the system. There are pros and cons to this. The con, potentially, is that I could get a little more motor-borne vibration at higher spindle speeds. The pros are faster start/stop and (likely) less vibration since the thing was not perfectly balanced to begin with, it now weighs a lot less and it has a vastly smaller polar moment of inertia for any unbalance to leverage.





Machining the deck down was pretty simple, too. The bottom of the head has two machined co-planar surfaces, so it was just a matter of getting it on the bed and clamping it. A 3/4" end mill cleaned it up nicely.











Since the mill is manual, I nibbled things close to the spindle bearing boss. Final cleanup can be done with a file. It needed to be somewhat close to clear the opening in the belt housing.



Finally for the day, I made the required hole in the motor mount bracket. This allows finger access to the nut (lol?) which will lock the bottom of the assembly to the head to eliminate wobbling.




So that is it for now. I will need to cut the belt housing a bit to clear the motor adapter plate, and do all the stuff with the new motor shaft & adapter. That is probably next weekend's project, or maybe this week after work if I can find the time.

[flyboyx]

that is indeed a whole lotta awesome! good job. this will be amazing when you are done.

following OP's lead,i picked up some parts for my drill press too. not to jack your thread, but i wanted to post them and thought it would be redundant to make another thread.

i went with the traditional way we talked about above.




This is my mid 1960's, made in the usa, medium size floor model Craftsman press. it came to me with the pictured 1/2 hp induction motor.





from ebay, i picked up this 2hp DC perm magnet motor for 65.00 shipped. it is brand new and never installed. it even has a cooling fan on the back end. i really like that it came with a nice mounting bracket that will fit perfectly against the original plate. 4800 rpm at 110 volts. the controller has a max output of 90 volts, so at full speed it should be running at about 4000 rpm. you will notice there are two Boston Gear ratiotrol boxes in the photo above. the one on the far right with reverse(that i don't care about) doesn't work. however, the middle terminal on all five diodes has been clipped off. i think perhaps if i replace them it may be fine. that one cost 35.00 shipped. the controller on the left, connected to the motor in the pic cost 52.00 shipped and it works great. I think that if i can get the non-working one fixed, i will try installing it on my table saw.

so, i have about 120.00 invested in my upgrade not including the controller that doesn't work. i still need pulleys and belt.. my setup has a 1" shaft on the headstock and 5/8" on the motor. i like the idea of using a serpentine belt, so i think i will get them off cars in the junk yard and machine the shaft hole to fit my needs. i would like a max speed of 8000 rpm, so i am thinking a 4" pulley on the motor and one half that size for the headstock. planning to modify the motor mount bracket on the drill so it is more steady as bmwman did in his project. i think it would be a good idea to take my headstock apart and clean it all up-possibly replace the bearings also.




here is a little youtube action vid i made.

https://youtu.be/VoUZ8b9VZf8

i think the motor is pretty quiet. it is certainly good enough for my needs.

[flyboyx]

i finished this project up today.



I used my lathe to make adapters for these pulleys. the one on the motor came from the water pump on an e36. the one in the foreground came off a junkyard mercedes.

a couple pics of the machining:














here is a youtube vid:

https://youtu.be/Nbv6eavNNSI

im pretty happy in total. in practice, the high rpm is probably much faster than i'll ever need or use. eventually, ill probably switch to a smaller pulley on the motor. a little more motor rpm would give me more torque on the low end.

[bmwman91]

Super cool! Good job on getting it done...clearly I have over-complicated my setup lol.

I am mostly done with the custom machined parts and stuff, and just need to finish the shaft adapter bits to get the new pulley to be driven. In the last couple of months I picked up a 2006 Jetts TDI as a spare car for the impending E30 repaint, and of course it has turned into a new project vehicle despite telling myself it was not going to be a project vehicle! Anyway, I'll get some updates in here with my drill press project soon enough. God help me, I hope that the scooter motor I bought actually works for this!

[bmwman91]

Holy shit, it has been almost a year since I last posted in here. Between COVID, blowing the HG in my 2.1L M42 and getting it rebuilt and "life stuff" I let this project fester for way too long. I am nearly done with the conversion, and it is pretty damn cool. Sadly, for the money I put into everything on this drill press, I could have bought a brand new Nova Voyager and had everything I wanted right out of the box. Then again, we all roll around in creaking 30 year old German steel boxes when many of us could have bought a newer "better" sports car for the same money, so I guess that this is the tool equivalent of what we do with E30's.

I have a load of pictures & CAD shots to put up here when I am done. At this point I am just finishing the design for the 3D printed enclosure for the controls / touchscreen. Yeah, my drill press has a touchscreen interface now lol. It's the future and shit. More to come...

[flyboyx]