South Bend 14 B 2 A Drill Press- Motor Upgrade

[Ulma Doctor]

I have a wonderful South Bend 14" Drill Press that i got from fellow member @TAWP Tool



i tried to utilize the drill press with just the OEM pulleys from the 56 frame 1725 rpm, 1/2 Hp motor @115v, for a couple years-



but the spindle was turning waaay too fast for my taste or use. (even in the slowest speeds possible) for much more than a 5/16 drill bit.
for woodworking and soft materials it was sweet to use,
large bits were out of the question.

i'm aware that there was another pulley arrangement available that gave more speed reduction,
but i was looking for a simpler answer...

through sheer luck, i was able to procure a 56 frame 1140 rpm, 3/4Hp motor @115v (inexpensively ),



i decided to use the stock pulley arrangement without further reduction.
i decided to calculate the approximate spindle speeds given what information i have available

the drive and driven pulleys are thankfully just inverted versions of themselves, giving 4 different possible speeds.
largest step 5.125" OD
next step 4.125" OD
next step 3.125" OD
smallest step 2.125"

to my best estimation, here were the old spindle speeds on the 1725 rpm motor arrangement
with the speed arrangement set to the lowest possible spindle speed, then increasing for each subsequent step
here is the reduction multipliers i used with the given 1725 RPM
step 1- { 2.412
step 2- { 1.321
step 3- { .758
step 4- { .415


Spindle Speeds:
716 RPM
1,308 RPM
2,279 RPM
4,161 RPM

after doing the calculations on the 1140 rpm motor arrangement,
you'll see there is a wonderful reduction
i used the same multipliers, but inserted the given as the 1140 rpm

New Spindle Speeds !:
473 RPM -243 RPM -33.9%
864 RPM -443 RPM -33.9%
1,506 RPM -773 RPM -33.9%
2,7450 RPM -1,411 RPM -33.9% from the OEM arrangement YIPPEE!!!!!


I used a string wrapped around the pulleys in the low speed position to estimate the belt size,
i ended up with a 4L460 belt and it fits like a glove!

the wire up was simple and went easy to install!

Here is some pic's of the motor as installed,





i'll be testing over the next couple weeks.

i already like the speed reduction


as always thanks for reading

 

[woodtickgreg]

Very cool! I've been taking things in a different direction but to gain the same thing, only it's not as cheap. D.C. motors out of treadmills with vfd's to run them. The vfd part is the expensive part. But the variable speed is the berries!

 

[Ulma Doctor]

Very cool! I've been taking things in a different direction but to gain the same thing, only it's not as cheap. D.C. motors out of treadmills with vfd's to run them. The vfd part is the expensive part. But the variable speed is the berries!

thanks Greg!
I considered going 3 phase and almost did,
but the 1140 rpm 115v motor, was an offer i couldn't refuse!
(i did the conversion for less than $150)

 

[benmychree]

Very cool! I've been taking things in a different direction but to gain the same thing, only it's not as cheap. D.C. motors out of treadmills with vfd's to run them. The vfd part is the expensive part. But the variable speed is the berries!

Variable frequency drive (alternating current) with a direct current motor?

 

[Ulma Doctor]

Variable frequency drive (alternating current) with a direct current motor?

Greg may have been referring to DC PWM (Pulse Width Modulation) speed control
stock OEM drivers for treadmill motors like the MC60,MC40, and similar designs are PWM.
and yes they can become pricey whether AC control or DC control

 

[mattthemuppet2]

very nice! Slower is usually much better than faster with metal, that's for sure.

If you ever get your mitts on a nice treadmill motor and an MC60, I'd really strongly recommend checking it out. I use mine for drilling up to ~1600rpm and tapping down to 50rpm all on one pulley ratio. I have one faster ratio (up to ~3000rpm I think) and one slower for using bigger drills in steel.

 

[benmychree]

Happily, I have been able to avoid/resist the seemingly mad rush to incorporate these devices onto my machine tools; the closest that I have come is using a DC magic box to operate the blower on my coal forge, using a DC motor, it made a very nice job, very quiet (until the fan bearings start to rattle at higher speeds). The forge, a Champion, had a ratchet lever/gear/belt drive, but had missing parts, hence the conversion. The control that I used was a simple one from Grainger.

 

[benmychree]

Sorry, but I am still using my treadmill motor for the intended purpose, my cardiologist insists that I do a regular routine on it, I don't think he would like to hear that I have repurposed (a word that I hate) it. Seems like I see fewer of them alongside the road these days, guess that they are no longer in fashion ----

 

[mattthemuppet2]

ha, I've used more treadmill motors for purposes other than powering a treadmill than I ever have seen used as an actual treadmill We even have a nice one upstairs with a monster of a motor in it, that I had to remove so my neighbour and I could even get it up the stairs!

TM motor = poor mans 3ph + VFD. If you have other means of getting variable speed on your machines or simply don't see the need for anything other than fixed ratios via belt or gears, then TM motors have no purpose in your shop. If that doesn't apply and a 3ph motor + VFD is out of the budget, TM motors are pretty darned awesome. Each to their own.

 

[woodtickgreg]

Variable frequency drive (alternating current) with a direct current motor?

Oops, lol.

Greg may have been referring to DC PWM (Pulse Width Modulation) speed control
stock OEM drivers for treadmill motors like the MC60,MC40, and similar designs are PWM.
and yes they can become pricey whether AC control or DC control