Why the Gear Reduction?

Topics related to wrapped rotary machining in Aspire or VCarve Pro
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Jeff Johnson
Posts: 49
Joined: Mon Apr 12, 2010 2:53 am

Why the Gear Reduction?

Post by Jeff Johnson »

I just started a build of an 96X48 router out of 80/20 and CNCRouterparts stuff. I am very interested in adding the rotary indexer to mine while I am building. Glad I found all this before I really got going. I have a stupid question? Why do these have to have a gear reduction? Is it for more tourqe? If its to slow the motor down, cant that be done when the toolpath is layed out? I have a lot to learn, and I spent all day saturday, and sunday reading all I could. Its amazing whats out there to read, but frustrating kinda also because there is never enough to actually pull the trigger in a certain direction, exspecially for parts. Right now the direction I think I am headed is to buy a cheap lathe of of ebay (139.00 free shipping) and just convert , or retrofit it with a pulley 10-1 ratio to my stepper. Am I on the right track? Also I have had operated Cut-2D for about 2 years now on a smaller table that I previously built. So how much of a learniing curve is there for the upgrade to carve pro. I really want to add this rotary, I currently cut material for a sign compnay but i want to expand to furniture with my nephew. So any help on wich direction to head on this would be greatly appreiciated.

Jeff

spinningwood
Vectric Wizard
Posts: 338
Joined: Wed Aug 12, 2009 2:09 am
Model of CNC Machine: Taig Mill and Self Built Routers
Location: Space Coast, Florida

Re: Why the Gear Reduction?

Post by spinningwood »

The gearing will control your resolution as well as your torque. Drive torque is not as much of an issue as holding torque. My 300 oz-in stepper can spin a couple hundred pounds of wood with no problem at 5:1 (t5 timing belt/pulley), but the larger the diameter and the more aggressive the cutting the greater the back driving force. I have to be really careful on work over 7" diameter.

Resolution is easy to calculate and plan for. That worked out great for me. Holding torque was beyond my ability to calculate and what I have is barely adequate for some really large projects (14" diamter). My next upgrade will be to add a planetary gearbox (probably 10:1). I don't need the extra resolution, but the gearbox will give me way more holding torque.

I've been happy with the cncrouterparts stuff, but someday I will upgrade to real linear bearings. Maybe after I win the lotto. Good luck.

Ed

RhoTu
Vectric Craftsman
Posts: 162
Joined: Mon Dec 29, 2008 10:12 pm

Re: Why the Gear Reduction?

Post by RhoTu »

See this thread and the response to my question which is basically the same as yours.

http://www.vectric.com/forum/viewtopic. ... 3&start=15

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