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  #1  
Old Sat 07 November 2009, 20:25
hansrange
Just call me: HansR
 
British Columbia
Canada
some R&P Q's

Hello all!

just a few questions:

1.) What are the benefits of using steel gear rack vs brass? beneficial property's of brass racks?

2.) What is the best y axis mounting configuration, and do most people Bolt through the side of the rack or clamp the rack into place?

3.) Rack "modules" measurement, what is being measured?

4.) Is there anyone using helical R&P should i choose this over the spur gear ?

5.) Metric sizing rack and pinion source, where?

Any additional information on optimal Rack and Pinion setups will be appreciated.
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  #2  
Old Sun 08 November 2009, 06:30
riesvantwisk
Just call me: Ries #46
 
Quito
Ecuador
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just a few questions:

1.) What are the benefits of using steel gear rack vs brass? beneficial property's of brass racks?

Brass racks and pinions might be (very) hard to get in some countries (in my country it was already impossible to get racks at all). The Mechmate was build in mind that you could build it all over the world with standard materials.

I am not a material expert, but isn't brass software then steel??

2.) What is the best y axis mounting configuration, and do most people Bolt through the side of the rack or clamp the rack into place?

I am not into this stage of building yet (but close to..)
I think the racks are bolded only on the very ends to the L rails and in the middle it's 'taped' with 3M double sided tape to the L rails. This is how I understand it currently
I think bolding through the site of the rack is not a good idea and best is to put it on the rails.

3.) Rack "modules" measurement, what is being measured?
- Sorry no answer, but I have seen a resent forum thread about this.

4.) Is there anyone using helical R&P should i choose this over the spur gear ?
- Sorry no answer (you can search the forum, may be somebody mentioned it...)

5.) Metric sizing rack and pinion source, where?
I got my racks and pinions from driver-motor.com

Any additional information on optimal Rack and Pinion setups will be appreciated.

What's optimal??
Every optimal setting often has a counter affect of something else, optimal highly depends on what you are planning to do with the machine.

However, most people tend to use a beld reductions to get better cutting results. My initial machine will not have that, but that is planned after the system works.
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  #3  
Old Sun 08 November 2009, 07:38
Castone
Just call me: Leo #41
 
Soddy Daisy , Tn
United States of America
Rack

I think that the steel rack and pinions are the best fit for the machine. I have purchased and inspected several high end machines , plasma machines that drill and mill and part mark all in one and laser cutting machines. All of them use R&P I have only seen one machine so far that is using the helical rack , but the spec for accuracy was no better than the other machines. We have a MG plasma at work it is about 19 years old using R&P it is setup just like the MechMate and we have never had to do anything to the R&P the gantry on it is quiet heavy it carries a drill a plasma head and a oxy head. I have changed motors on laser machines that were several years old , but I have never had to change the rack of coarse these are hardened. So I think it is a waste of time to be trying anything else , I would be sticking to what is a proven fact the MechMate R&P works and it has been proven on many different types of machines. I have seen a few places use some type of nylon pinions to make the machine quieter but PM logs show that they had to be changed a couple times a year. But they were using the steel rack. Just my thoughts on it as far as mounting I just use the tape .
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  #4  
Old Sun 08 November 2009, 07:44
isladelobos
Just call me: Ros
 
Canary Islands
Spain
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I think the best option are the linear motors but this is other history

Last edited by isladelobos; Sun 08 November 2009 at 07:46..
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  #5  
Old Sat 14 November 2009, 06:39
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
For helical rack you introduce a sideways force on the gear pinion. Any sideways float of the pinion becomes linear backlash in the cutting motion.
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