[ikhan42]

Hey guys I found this site that guarantees zero backlash rack and pinion system anyone have any experience with this or know anyone who has used this in a system am a little skeptical that there will be zero backlash.

thanks
ikhan42

[ger21]

Can you post a link to the site you're talking about?

[ikhan42]

Sorry thought I had pasted the link here it is

http://www.nexeneurope.com/en/model/rps-classic.php

ikhan42

Can you post a link to the site you're talking about?

[mike_Kilroy]

I'm more than skeptical. as an AIME certified motion control engineer, I cannot see any physics that matches our euclidean math that might make this design "0 backlash."

Ok, I can accept claims that life may be extended by roller bearings on the meshing 'teeth.' but there is nothing here I see that could possibly in my mind equate to "0 backlash." to get 0 backlash from a rack/pinion, you need some method to make the space between teeth and rack zero - this does not do that.

I vote bad advertising.

[ikhan42]

There are alot of good writeup's on this setup but I dont think I can justify costs and im guessing its very expensive as there are no prices on the website and the suppliers here in australia arent responding to enquiries.

Guys are the split pinions expensive and any one know where I can buy rack and split pinions in sydney australia.

I am very keen to start building the cnc as I have a bunch of working projects that I need to do at hom that I have been putting off for years and now more projects are being pushed my way as our house is getting older (so am I ) I am also wanting to design a simulator and make all the dial instruments my self with aluminium face plates and am guessing a cnc machine for cutting the dials and also etching the numbers would be a good thing for me to invest in. Hey might even help me understand gears to make the instruments.

I am sure I will have a million more questions as time goes by.

regards
ikhan42

I'm more than skeptical. as an AIME certified motion control engineer, I cannot see any physics that matches our euclidean math that might make this design "0 backlash."

Ok, I can accept claims that life may be extended by roller bearings on the meshing 'teeth.' but there is nothing here I see that could possibly in my mind equate to "0 backlash." to get 0 backlash from a rack/pinion, you need some method to make the space between teeth and rack zero - this does not do that.

I vote bad advertising.

[mike_Kilroy]

ATLANTA Ultra-High Precision Rack & Pinion Drive Systems

has a good name.

I recently helped diagnose a shaking problem on a rp dual system that used Y shaped bearings riding on top of thomson shafting. the 5000# gantry was not heavy enough to prevent it LIFTING as the clearance was to tight - causing the shaking they were trying to prevent! anyway, you need to check specs to see if a split pinion is good enough for your need. an alternative is a spring loaded dual pinion box but they start getting expensive. then you can use an antibacklash servo system like we sell with dual servo motors and dual pinions on same rack but that too is expensive.

[ikhan42]

Mike,

I had a look at the atlanta site yesterday I likes the dual pinion dual motor setup. As I mentioned its not going to be a industrial machine its going to be doing stuff like kitchen cupboard doors, shelves, the instruments for the flight sim though I am thinking on building a mini mill for circuit board and the flight sim instruments.

How much are the dual pinion systems with anti backlashing servo, everyone I as for a quote from their web site requests seem to not respond to inquiries.

Also a question cant I just make a plate with 2 pinions on it connected together with 1:1 ratio gear so both pinions rotate at the same rate? would this not fix the backlashing issue. Even better couldnt I do that with dual split pinions ?

Also the antibacklash servo you are referring to I thought its the rack and pinion that cause the backlash not the motor.

ikhan42

ATLANTA Ultra-High Precision Rack & Pinion Drive Systems

has a good name.

I recently helped diagnose a shaking problem on a rp dual system that used Y shaped bearings riding on top of thomson shafting. the 5000# gantry was not heavy enough to prevent it LIFTING as the clearance was to tight - causing the shaking they were trying to prevent! anyway, you need to check specs to see if a split pinion is good enough for your need. an alternative is a spring loaded dual pinion box but they start getting expensive. then you can use an antibacklash servo system like we sell with dual servo motors and dual pinions on same rack but that too is expensive.

[ger21]

Those cost about 10 times more than regular rack and pinion, which is probably why I haven't seen anyone using them.

[svenakela]

...at a speed 10 times higher than regular rack and pinion.

[ger21]

Just about everyone here building rack and pinion machines uses a basic single pinion, spring loaded into the rack ala cncrouterparts.com
There's really no need for the greater expense of split pinions for what you'll be doing.

[ikhan42]

Ger,

Thanks for the info have had a look at the cncrouterparts.com website and they are pretty much a one stop shop for parts.

I am putting an order in for the parts I need for the table but have noticed that they have the pinion included in their rack and pinion spring loaded kits however they dont seem to have the rack. I am guessing the teeth on the rack and pinions are an international industry standard and any rack that matches the 20pitch will suffice globally is this correct?

Also is there any rule of thumb of what motor to use I am not sure wether to use the nema23 or nema34 motors i am leaning towards the larger motor but am thinking maybe for what I am using this for the motor may not be a good thing. Is there also any reason why I cant use the nema34 for the x axis and the use the nema23 for the y and z axis.

thanks
ikhan42

Just about everyone here building rack and pinion machines uses a basic single pinion, spring loaded into the rack ala cncrouterparts.com
There's really no need for the greater expense of split pinions for what you'll be doing.

[ger21]

The rack is 20° pressure angle, 20 pitch. There are different pressure angles and pitches available. Make sure you get the correct one. If you can't find them in Australia, see if Moore Gear can ship to you.

Also is there any rule of thumb of what motor to use I am not sure whether to use the nema23 or nema34 motors

The proper way to choose a motor is to calculate the required torque to accelerate the weight you have to move to a target velocity at a target acceleration rate.
Most new to CNC have no idea what they want or need.
So they just go with the Nema 23, which works fine in most lighter weight machines. If you're moving 150 lbs or less, they should be OK.

[ger21]

I am looking at a 5 by 4 foot machine used for wood, thin aluminium, and steel maybe

Cutting steel with a router is almost never an option. Cutting steel typically requires much lower spindle speeds, coolant, and far more rigidity than routers typically possess.

What kind of budget are you looking at? I'm going to guess that the Kollmorgen setup will be at least 3 times the cost of the CNC Routerparts setup that almost everyone here uses.

[ikhan42]

Ger,

I wasnt looking at putting a "router: on the cnc machine was going to use some kind of motor with speed controls that will be controlled by the cam software. From what I have read I will need something like an r8 collet to hold the bits.

Was going to ask down the track what is good to use as the machining device.

thanks
ikhan42

Cutting steel with a router is almost never an option. Cutting steel typically requires much lower spindle speeds, coolant, and far more rigidity than routers typically possess.

What kind of budget are you looking at? I'm going to guess that the Kollmorgen setup will be at least 3 times the cost of the CNC Routerparts setup that almost everyone here uses.

[Al_The_Man]

I suggest you also get hold of the Misumi catalogue, they cover Australia.
Al.

[ikhan42]

They dont seem to have a presence in australia all I can find is Japan, Taiwan, Singapore, USA, and UK. Will keep looking thanks for the advice.

I suggest you also get hold of the Misumi catalogue, they cover Australia.
Al.