Gear Rack Sources-10ft.

[utahnorton]

Does anyone have a source for gear rack in 10ft lengths (with mounting holes) at a reasonable price. I'm thinking 24 pitch for a plasma table.
Most of the usual sources-Mcmaster Carr etc all have 6 ft listed as the longest length available and I want one piece for accuracy and ease of assembly.

Thanks,

Tom

[mxtras]

I would not be concerned with finding a single, 10' piece. Take two pieces and gap them correctly and pin them in place. They can be gapped pretty close in less than a few seconds by taking a short piece of rack and inverting it then clamping it across the joint. This will get you within the manufacturer's tolerance for pitch error.

I used to assemble rack driven machines that were up to 180' long (Ultrasonic cutting tables for Boeing mainly) and this was the method used. An 8' table would have a seam and then there were seams at the start and end of every 8' section - a lot of seams down the length of the machine.

For a better gap transition, use a gage pin in the teeth and a test indicator on the motion platform. But 9 times out of 10, the inverted rack method gets you pretty damn close - you won't hear, feel or see the transition if the installed pitch height is in the same ballpark. Make sure to de-burr the rack before you install it and mic the height and try to dimensionally match the ends.

Scott

[Al_The_Man]

With the unfinished rack you have to make sure you cut the end just short of the tooth valley because the pinion does not bottom out you can tolerate a small gap, and use the method previously mentioned by using a length of rack as a mounting aid, if you want precision rack with pre-machined ends and mounting holes, Sterling products sell a nice hardened rack, but expensive.
Al.

[utahnorton]

Thanks Scott & Al,

I am capable of mating sections of gear rack together as I have a small machine shop but I'm also real fussy on how I put things together. I'm sure I can mate sections of rack together but if possible I would rather use one piece hence the problem of finding 10 ft. lengths. I'm going to run two servos on the gantry so I'm looking to buy 2 ten footers and a 5 footer. I tried doing a Google search on Sterling Products but didn't come up with a company that manufactures gear rack.

Thanks,

Tom

[Al_The_Man]

Sorry, they go under a couple of names, their site and the catalogues they have, have a wealth of engineering data in them.
http://www.sdp-si.com/
Al.

[utahnorton]

I think I found a source for my 10 ft racks after getting quotes from several
companies. My price for a 24DP-20PA with a 1" face width X 1" thick with
counterbored holes in the face (lower .5 in where pinion won't run) for side mounting 1/4-20 socket cap bolts every 12 " is $286.29 ea delivered. I am going to order 2 since my gantry is going to run two servos. Will probably order tomorrow. If anyone else is interested contact me asap and I'll see if there would be a better break for a larger quantity. Lead time is supposed to be 4 weeks. The other quotes I got were almost double that. These are custom made in the US. If interested contact me at utahnorton@sisna.com

Cheers,

Tom

[ericdwilso]

Would you mind letting us in on who the vendor is? Eric

[RICHARD ZASTROW]

You might try Martin Sprocket & Gear www.martinsprocket.com

[low_48]

I had a Digital Tool machine in the mid '80s. The bed was 8' wide overall, and it had a 1" axle from side to side to drive on the two rack gears, one servo motor for the two racks. There was a pillow block in the center to limit the torsionals.