New Products Flash Sale
Thread Tools
Old Mar 21, 2012, 03:58 PM
tom43004 is offline
Find More Posts by tom43004
Father of Fr3aK, DLG Pilot
tom43004's Avatar
Build Log

"Gearing up" for another CNC build thread


Kinda... over the next week or ten days I'll be converting my Joe's 4x4 CNC from lead screw to rack and pinion. I originally started building my machine in November of 2009 and have been cutting with it regularly for just over two years.

The pictures seen here are taken on the current machine, and are parts that I'll use to convert it to RnP.
Sign up now
to remove ads between posts
Old Mar 22, 2012, 08:12 AM
tom43004 is offline
Find More Posts by tom43004
Father of Fr3aK, DLG Pilot
tom43004's Avatar
Belt reduction kits showed up yesterday... very nice stuff from cncrouterparts.com

BTW the rack came from Moore gear. Thursday call and Tuesday UPS truck with a custom drilled rack. GREAT service.
Old Mar 22, 2012, 09:55 AM
mlmcquiggjr is offline
Find More Posts by mlmcquiggjr
Registered User

I was Harry's Cast CNC #44


I am in the final stages of finishing up a smaller V 2.5, looks like my cut area will be 22.5 x 48 inches.
Old Mar 22, 2012, 10:40 AM
tom43004 is offline
Find More Posts by tom43004
Father of Fr3aK, DLG Pilot
tom43004's Avatar
Very nice. A friend of mine is doing a Harry's cast CNC too...
Old Mar 22, 2012, 02:23 PM
ptxman is offline
Find More Posts by ptxman
Registered User
Quote:
Originally Posted by tom43004 View Post
I'll be converting my Joe's 4x4 CNC from lead screw to rack and pinion. .
Neat, thanks for sharing. CNC's helping to make their own replacement CNC's!
Dumb question, but what does the rack & pinion enhance? rigidity... positioning... backlash issues... transit time...?
Old Mar 22, 2012, 03:47 PM
tom43004 is offline
Find More Posts by tom43004
Father of Fr3aK, DLG Pilot
tom43004's Avatar
Yeah, my CNC has spawned parts for half a dozen or so others, as well as cutting some part modifications for itself.

As for RnP...

It's a little more forgiving of slight racking issues on a homebuilt machine, and increases my rapids since I'm not spinning a 6 foot long leadscrew anymore. It also eliminates couplers which can be a PITA to keep from slipping.

The big reason is that it increases my cutting area by about 40% without changing footprint since the pinion can run right to the end of the rack, where the leadscrews have boxes that carry a bearing on each end and the stepper, all of which deduct from travel. Right now I have seven inches of unusable table at the front and back of my machine and with RnP on the Y/A axis I get to reclaim all of it in the front and most of it in the back.

Gearslop is very similar to or a little better than the backlash on standard ACME screws, and drag is quite a bit lower, especially if you upgrade to a ball screw for more accuracy. All of this makes a more maintenance free, faster, cleaner machine with a larger cutting area.
Old Mar 22, 2012, 05:55 PM
Merk is offline
Find More Posts by Merk
Registered User
Merk's Avatar
Tom Looking good.
Soon I will be calling you for some simple test files for my CNC.

Russ
Old Mar 23, 2012, 12:17 AM
tom43004 is offline
Find More Posts by tom43004
Father of Fr3aK, DLG Pilot
tom43004's Avatar
I have you covered Russ. Just let me know when.

You should probably start with a 1/2 ballnose, a 1/4 endmill, 1/4 ballnose, 1/4 endmill .060 radius, and maybe a 1/8 collet with 1/8 endmill and 1/8 ballnose. Those will cover most situations for now.

I probably have over 100 different bits now and 5-6 different collets. It's really a bad addiction. You start losing sleep trying to figure out how to match a tool to a part (of a part) so that the machining is perfect. Next thing you know your credit card is maxed out on little chunks of carbide.

Tom
Old Mar 23, 2012, 11:04 AM
tom43004 is offline
Find More Posts by tom43004
Father of Fr3aK, DLG Pilot
tom43004's Avatar
One of my favorite uses for my CNC is as a router table. I'm using a 1/8 roundover here to clean up the edges of the parts for my new X axis carriage.

Time to paint on 8-10 coats of wood sealer so I can do finish sanding and assemble with epoxy.

My McMaster order arrived yesterday so it's officially on this weekend.


DSCF4578.AVI (0 min 24 sec)
Old Mar 23, 2012, 03:40 PM
Merk is offline
Find More Posts by Merk
Registered User
Merk's Avatar
Tom,

I to rounded all the edges before gluing it all up. Makes it look a litlle better.

That wood hardener stuff is great but don't get it on your hands.
It turns them a nice shade of black for a few days.

Russ
Old Mar 23, 2012, 03:50 PM
tom43004 is offline
Find More Posts by tom43004
Father of Fr3aK, DLG Pilot
tom43004's Avatar
Yeah, I have used it a bunch of times in the past, including on my current CNC.

I think the roundover and a good coat of paint keeps it from looking like a homebuilt machine. No sense in building something ugly after all.

BTW... I should have a box ready for you by mid week next week.
Old Mar 25, 2012, 10:42 AM
tom43004 is offline
Find More Posts by tom43004
Father of Fr3aK, DLG Pilot
tom43004's Avatar
Sealed, Painted (first two coats) parts

Today I get to glue together the carriages. If I didn't have to play hockey tonight I'd probably get the wiring harnesses updated. Today the Y/A axis motors are fixed at the back of the machine, on bearing blocks mounted to the 8020 and hardwired back. With the RnP mod, the motors will be on the carriages, moving with the gantry so I need to reroute cables, probably make new ones, and wire more "stuff" into the gantry wiring harness.

BTW... this is how messy your machine will look in a couple of years if you actually use it. It's surprising how much static electricity the dust removal hose generates (even with a ground) and how the statically charged particles stick to the wall behind the machine.
Old Mar 26, 2012, 10:08 PM
Aerogance is offline
Find More Posts by Aerogance
The hobby is back! Lets fly!
Aerogance's Avatar
A few moments with a push broom will have that wall looking like new
Old Mar 29, 2012, 08:13 AM
Merk is offline
Find More Posts by Merk
Registered User
Merk's Avatar
OK,
Tom is it all together?

Like to see some pics.

Russ
Old Mar 29, 2012, 08:40 AM
tom43004 is offline
Find More Posts by tom43004
Father of Fr3aK, DLG Pilot
tom43004's Avatar
I'm taking lots of pics Russ. I had an issue with the paint not wanting to dry over the weekend here (raining / humid) so I have all of the carriages painted and assembled now.

I had to find a local supplier for bushings since Ahren sent me the R&P kit with a 1/2 pivot instead of the 3/8 that I'd ordered. I just got the bushings last night and I'll press out the old ones / press in the new ones tonight. Assembly doesn't look like it will take long so I may take a stab at it tonight.

The wiring will take longer than anything else.


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Build Log Another Scout Bee build thread flylite FPV Talk 27 Oct 09, 2013 03:31 AM
Discussion Another bladder molded pod/boom build thread danstrider Hand Launch 20 Mar 02, 2012 06:40 PM
Discussion Another test of Changing thread description test of Test thread for next year Prof100 Foamies (Kits) 4 Dec 18, 2011 10:28 PM
Discussion Build thread of cnc bearing servo tray for your high performance models kin Multi Task F3X 9 Oct 30, 2011 08:05 PM
Discussion Another P.S. Build Thread TheWoodCrafter Batteries and Chargers 2 Oct 07, 2011 11:14 PM