[acourtjester]

HI All
I am looking for an article posted in The Home Shop Machinist or Machinist Workshop that I lost.
This article is about a variable speed “V” belt drive system used on a drill press or small mill. This is a simple setup using a double pulley mounted on a jackshaft with a handle for movement. I believe the top and bottom parts are fixed and the center part moves up and down. This happens when the handle is moved and the belt pressure moves the center part up or down and changes the ratio of the pulleys and the speed of the output shaft. I saw one on a drill press many years ago and wish to build on now.
Any help would be welcomed.

Attached pictures are of a modified drill press and lathe using this system to manulaly very the speed.
Thanks
Tom

[eshreve]

I think the center pulley was from a "shift on the fly" type riding mower, mabe an mtd. A lawn mower repair might be able to recognize it.

[NEATman]

Hi Tom-
I don't have the articles, but I know that the variable speed belt drives are used on some washing machines, and a simmilar drive can be purchased for gocarts.
http://www.northerntool.com/webapp/w...70_21024_21024
It may get you a good start, and you may be able to modify them to what you need.

From the pictures that you posted, it appears that the motor and the spindle pulleys are fixed, while the center pulley is shifted closer or farther from the motor/spindle and the center pulley varies the diameter of both pulleys at the same time.

I have a 9" southbend, and if you come across the articles, I'd love a copy - as a retrofit would be nice.

Keith

[acourtjester]

Hi
Thanks for the replies.
The Go Cart type pulley works with a increase of the motor speed and will not do what a variator will do. And not what I need for my project.

Keith you are correct about the operation of the center pulley they seem to work great. and are cheaper than a electric variable speed motor.
The attached pictures are from lawn tractors, the green one is John Deere. You may go to Ebay and search for "variator" and you will find one for sale. That may help you to modify you lathe.
have fun
Tom:wave:

[LeeWay]

I think some of the more recent Delta drill presses used something like this. Never had one, nor looked at the guts, but I think this was the way they worked.
http://www.deltaportercable.com/Prod...roductID=15684

http://www.dewaltservicenet.com/Prod...cumentId=35623

[chich2]

Tom,
Is this what you are looking for?
http://www.lovejoy-inc.com/uploadedF...talogs/vsd.pdf

Chich

[acourtjester]

Hi
Thanks for the replies both are similar to what I am looking for. But both of them are single adjustable pulley systems. If you look at the pictures I posted you can see the center pulley is a double adjustable pulley. As the top gets larger the bottom get smaller and vice versa. Just like switching the belt on a stepped pulley system. This gives a much wider range of speed changing. This acts like the stepped pulley system in moving the belts to different size pulleys to change speed. But it is done on the fly and with just moving the center pulley shaft postion, which makes each of the center pulleys change size.

Have fun
Tom

[Bubba]

I think Grainger used (many years ago) have a stand alone adjuster like that and as I remember, it was like a 9:1 ratio.

IIRC, the pulley assembly moves at an angle to keep both sides aligned with its respective pulley.

[gandalf1]

Back in 1969 I used one of these variators,
Sadly not a very good photo having been scanned from a fading magazine. Basically it was a bracket with a pivot at the bottom, a locking knob at the top of a moveable lever that clamped onto the curved top of the bracket. On the lever about in the middle was a spindle with a Vee pulley which had a floating centre flange with a sort of diamond section. A belt ran from each side of the wide pulley separated by the floating flange so that move the lever one way and the belt tension reduced the effective diameter one side and increased it the other and so gave the variable speed ratios between driver on one side and driven on the other.
Hope this is the sort of thing you are interested in.
John.