Gearing Down A Jet Drill

[brino]

I will try, and see if it will work

Hi toolroom,

Did you make any progress on this?
I would certainly want two bearings in the idler pulley to resist any twist...or one very thick one.

-brino

 

[toolroom]

brino,
No progress. The motor has begun to make growling noises, and I see that I MUST go with a three phase 220V motor, ot scrap the unit and buy a really cheap Chinese one from Harbor Freight. Either $60.00 Chinese vs. $2000/$3000.00 for a new motor with a vfd.
Can't afford that yet, which is a shame as the Jet is a heavy cast unit and has a good spindle on it, but you can't drill holes with an anchor
Toolroom

 

[BobSchu]

Here you go-
http://www.ebay.com/itm/MOTOR-VFD-P...248572?hash=item1c5bbdc87c:g:MTIAAOSwa-dWn852

 

[mksj]

Was thinking the same thing, but would go directly to their website. Probably go with a 3/4 or 1Hp 1800 RPM motor depending on the pulley ratios.
http://dealerselectric.com/motor-drive-packages.asp

 

[BobSchu]

Agree, this is the one I was looking for but couldn't find at the moment-

http://www.ebay.com/itm/MOTOR-VFD-P...773260?hash=item54289f2d0c:g:EacAAOSwuYVWn-EB

Or, sell the DP you have now and buy this one and you'll be money ahead and have a better drill press to start with. I have two of these and they are killer drill presses.

http://portland.craigslist.org/mlt/tls/5495099482.html

Bob

 

[Dunc1]

I have followed along in the forum long enough to safely ask this question. I own an older Jet bench drill it is a single phase ? 120 volt 1/2 horse 1725 rpm motor. The pulley speeds on it are 500, 900, 1600, & 2800. Yowza, can't do much with this, so I only use the 500 rpm.
I have tried in vain to find a larger pulley for it but 1) Jet remains ignorant. 2) The Farm stores carry step pulley's with little room to bore the ID out...so, Should I replace the motor with a lesser rpm range? Try to install a VFD?
What would you senior member do to bring the rpm's down to a workable range?

Check out the Google reprints of old Popular Mechanics (PM) & Popular Science magazines (One eg is PM Mar 42). Another idea: (not my original idea but I could not locate a source). Remount the motor upside down on an auxiliary plate along with a ball bearing arbor. Place a small (2-2 1/2 inch diameter pulley) on the motor shaft and use it to drive, via another v-belt, a 10 or 12 inch diameter pulley on the bottom of the arbor. Place the original cone pulley on the other end of the arbor & have it drive the original pulley on the spindle.
Here's another concept:

 

[Smithdoor]

This is way I slow down my mill
Add a center pulley wend I need low speed
Note: The center pulley is very large and was shop made.
Use a larger small pulley on the center pulley so the belt dose not slip
Slow speed is 139 RPM with 1725 motor I have 2 speed motor and at 1140 the it is 92 RPM

Dave