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Posted: Wed Aug 10, 2011 8:51 am
by pennview
If you look here -- http://www.dynamicscience.com.au/tester ... mpound.htm -- you'll see an example of compounding. Do a google search on "compound gear train" for other details. Compound pulleys work the same way.

Posted: Wed Aug 10, 2011 11:50 am
by holsgo
It's making more sense now. That last diagram helped. Im going to think through the math more so I can do this without having to ask again in different configurations. I found a local place with pulleys and I'm excited to play. I need to cut some aluminum soon for a dremel mount for my tool post grinding attachment that I posted in my "upgrades" thread. Once I get it done I will post some pics of what I built. I made 2 attachments that can place bearings on moving parts while attaching to the way tubes so there is no dependence on the carriage location. I'm out of my mind I know.

Posted: Wed Aug 10, 2011 5:00 pm
by jm51
I'd go for a temporary connector made from hosepipe and add hoseclips if needed. Not 100% confident it will do the amount of work needed but it's quick to check it out.

Posted: Wed Aug 10, 2011 5:43 pm
by holsgo
I already did the temporary mount. Worked great thus moving me toward the solution of mounting the dremel with a real firm connection. There are 3/4 12 threads on the front of the dremel which allow for attachments. This is where I will be mounting the dremel to a fixture to my cross slide. I should post some pics of it in action as I've been able to do great work so far. I've been quite surprised as the progress.
Fog has cleared a bit on the pulley issues. Thanks guys.

Posted: Wed Aug 10, 2011 9:34 pm
by pennview
There's a guy on Ebay that been selling an adapter for some time for mounting a Dremel on a lathe. Not sure what you're building but you might want to take a look. See -- http://cgi.ebay.com/Dremel-tool-holder- ... 347wt_1159

Also, older Dremels have a different threat pitch on the nose of the tool than the 3/4 x 12 TPI.

Posted: Wed Aug 10, 2011 10:46 pm
by charlese
This speed reducer is a very nifty invention. I also got a bit confused trying to understand the math, but then came a eureka moment.

If it is understood that the 2" drive pulley to the 7" jack pulley lowers the speed to the jack shaft. - - Then the second speed reduction can be understood by looking at the second set of pulleys upside down. The eureka was to realize that both belts start with small pulleys and go to larger ones.

Posted: Thu Aug 11, 2011 5:55 am
by holsgo
Yeah, I've seen that holder but that's for a toolpost. I'm going to go a slightly different route. I found a site which went over some dremel options but since I'm mounting to a cross slide the action is slightly different because of the sides of the vice itself.