GearHeads Corner

I am interested in routing gears from plastics polycarbonate, delrin, polypro, and teflon.
Does anyone have any suggestions on types of cnc routers available or any specific recommendations or examples?
I anticipate my largest gear will be 18" diameter. Thx

Hi Rodd:

  There are, of course, infinite answers to that question. I use a chinese router, it can be seen  in several of my video's.
Many are now using machines like this one
http://www.ebay.com/itm/5-Axis-3040-CNC ... 25925b783c

  though I havent seen on ein operation. I hear their far from perfect, but with tinkering can be made to work very well. (Anyone had experience on one of these? )

Art

That 3040 would be a bit small for 18" gears.  These are also popular (never seen or used one, and this is a random pick), but it'll max out just under 16".  I have a smaller and older Zenbot (here's their 24x24) that I like, and if you poke around on cnczone.com you can find lots of reviews and discussions of many different smallish CNC routers.

If you're up for roll your own check out the ShapeOKO and Openbuilds OX, which can be expanded to at least 24x24.

Kirk

Take a nice long look at the ShapeOko 3.

The stock size is a little smaller than what you're looking for, but the extrusions are big and beefy and it will be possible to get longer lengths. Very active forum and Wiki as well.

Actually, the designer Edward Ford has said that they won't be selling extrusions or upgrades for a while, so at least for now the SO3 is a fixed size.  It's stirred up several people in the SO forums, ticked off some of the strongly opinionated open hardware people (who always seem to have other sources of income so their wives don't pressure them to move out of Mom's basement, but I digress...).  I haven't checked over there for a few weeks, so maybe there's better news on when upgrades might happen.

While the SO2 is still sold by Inventables Ed has left their employ and gone to another company for the SO3.  It'll be interesting to see how that whole thing plays out, but until then it might be best not to count on a ShapeOKO 3 expansion any time soon.

The Openbuilds OX is more of a roll your own choice, but Openbuilds has just introduced a C shaped extrusion that looks to be considerably stiffer and better suited to bigger machines.  If I ever get that new shop built out in my barn and have enough room for it,  building a 4 foot square version is pretty high on my list.

Kirk

Interesting. There's a VERY long thread regarding the SO3 on their forum and I haven't read it.

All that said, I'd have a hard time believing that it'll never be expandable. You don't make custom extrusion like that just to stay at 16" or whatever their build size is. Time will tell.

From what I've seen the specialized extruder sellers just can't keep up with the demand,  The minimum order from the companies that make the extrusion are big bucks for a small operation, and I'd speculate the sellers don't want to get stuck with a big pile of unsold parts so they stay close to minimum orders.  Even Openbuilds, who seems to be doing pretty well, is often out of stock.

From that perspective Ed Ford's doing the right thing by pushing expansion kits and bare extrusion off until it looks like there will be a decent market for them.  It also cuts down on support problems by only having one thing to deal with while they work the bugs (of course there will be bugs...) out.

While I don't have a shapeOKO I've corresponded with Ed on several occasions and think he'll get it all sorted out, but it'll take time.  In the meanwhile it's hard to cut those foot and a half gears, and the SO3 just misses it.

Kirk

Update:  I just poked around in the currently 191 page (of which about 180 are "are we there yet") SO3 topic, and found where Ed made a comment about the possibility of expansion packs in September/October, so that's changed since the last time I looked at it.  He mentioned getting some 6' extrusions so maybe a 48x48 or bigger version is a possibility.

Thread about S3 extended sizes:

http://www.shapeoko.com/forum/viewtopic.php?f=7&t=5987

The biggest gears and flywheels are made in sections. There is no embarrassment in this. Just make the joints look cool.

Perhaps build your own. Great satisfaction in going that route although it certainly takes longer and there are some cost savings but you can size it exactly the way you want it. Below is one that I designed and am just finishing. Having worked through a number of bugs, the next one will be far easier as I designed it so that it can be scaled up quite easily. Fortunately I already have a small CNC mill that I used to make many of the parts. My total cost will be about $3,200 Canadian. I already have the software but I think most any CNC router that you buy would come without software too.

JustinO wrote: The biggest gears and flywheels are made in sections. There is no embarrassment in this. Just make the joints look cool.

It may also be possible to cut on a piece of material that's larger than the working volume of the router.  That can work very well with the right jig, though it doesn't look like the SO3 will accommodate 18".

Depending on what your goals and materials requirements are are, you may also be able to economically hire a shop to make the gears for you. 

Nice work David, appears well built....

Cheers
Bob

Also look at CNC Router Parts designs...cncrouterparts.com

I built the CRP4896 Router 2 years ago (960 oz-in steppers with 3.2:1 reduction, Leadshine digital drives and a 3hp water cooled spindle..
it is very sturdy and has performed flawlessly...
I have about $6 grand invested.  

I can cut large gears with no problem..


This is an early photo after completion...

DHelmick wrote: Also look at CNC Router Parts designs...cncrouterparts.com

As it happens, I have my order ready for the motors & electronics that I have been discussing with them. But it's always nice to get a referral to good sources. Thanks.

Nice table. Looks powerfully built and well designed. Extrusions really
are great ways to build tables, I wish they had been around when I built my first table..
way back when..

Art