Bob's Super Simple 4th Axis

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Re: Bob's Super Simple 4th Axis

Postby NewAgent45 » Sun Apr 26, 2015 7:57 am

Ed,

Please check you private messages on the forum.

........ Rod
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Re: Bob's Super Simple 4th Axis

Postby EdThorne » Sun Apr 26, 2015 9:12 am

NewAgent45 wrote:Ed,

Please check you private messages on the forum.

........ Rod

Hi Rod, Sorry but I don't see any new message in my PMs. I'll keep checking.
Ed
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Re: Bob's Super Simple 4th Axis

Postby Kayvon » Wed Sep 07, 2016 6:21 pm

4.5 years later... it's not too late to reply, right? I have a few basic questions.

NewAgent45 posted some great pictures of his setup. Does anyone have plans for how I'd create the adjustable-length crossbeam? Because that looks extremely practical to have.

How are the wheels/pinions attached to the mounting arms?

And, lastly, where's a good place to buy HDPE for this?
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Re: Bob's Super Simple 4th Axis

Postby Bob » Wed Sep 07, 2016 7:10 pm

It's never too late...
For plans pertaining to a particular modification, use PM to contact the person who posted the idea.
Wheels rotate on a .25" shaft that is anchored in the arms.
An easy way to find HDPE is to use Google to find a plastics dealer near you. If they have an outlet store, even better. The material doesn't even have to be HDPE. For some parts I just used what I had in the shop.
Bob
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Re: Bob's Super Simple 4th Axis

Postby NewAgent45 » Thu Sep 08, 2016 6:42 am

Kayvon:

I ordered the HDPE from McMaster-Carr Industrial supplies online site.

I made the support arms first including milling the groves that the cross beams set into. I drilled and counter sunk the arms to accept two flat head machine screws in each arm and the ends at the cross beam are drilled and taped. The cross beam was trimmed to fit after mounting the support arms. The outer piece of the support arms are clearance drilled and inter is drilled and tapped. Standard 1/4-20 hex-head bolts were used for the support arms. You can loosen these bolts and tap the arms to achieve perfect alignment. I used two pieces of polished drill rod for the half shafts and ground a flat for a set screw to engage on each of the support arms.

We built this project without drilling any holes or making any modifications to the original machine. and it only takes a few minutes to install. The length adjustment relies on the T-Slot in the cross beam and the T-Slots in the spoilboard. The spoilboard T-Slots are cut parallel to the X axis so the rack can be adjusted with the slide support arm. I used 1" thick HDPE material for the cross beam and I notice some flex when the machine is running This makes it necessary to shim the left side rack a little bit so the gear wheel rides rack and the spoil board though the full travel length (y).

I hope this helps.

Have a great day!

.... Rod
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Re: Bob's Super Simple 4th Axis

Postby Kayvon » Thu Sep 08, 2016 4:04 pm

Great replies, guys.

Bob: So you have drill rod or something between the wheel and the support for the wheel/pinion to pivot on? Is the wood you're turning it just screwed onto the wheel? How do you fit it all into place without being able to adjust the length? I suppose you could remove and re-attach the support arms each time you use the tool.

NewAgent45: With your description, the pictures you posted make a lot more sense. And the McMaster-Carr suggestion was spot on--turns out I've ordered from them a couple times before but didn't realize they sold plastics. I also found that Grainger, a similar supplier, has a local branch I can grab supplies from.
Do you mind if I ask where you got the T-slot for the cross beam? It looks like what Rockler sells, which I'm sure is high quality but also a bit pricey.
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Re: Bob's Super Simple 4th Axis

Postby Bob » Thu Sep 08, 2016 10:24 pm

You are right, the wood is attached to the gear with screws.
I cut the wood to the length that fits between the support arms. Mine is not adjustable. Rod's and several others are adjustable.
In order to mount the gear/wood blank, I hold it between the support arms and slide in the .25" rod from the outside of the arms, into the holes on the gear. The rod is held in place on each arm with a thumbscrew.
You are also right about Rod's pictures of his setup. They show a very clear explanation of his method. He also provided a very thorough written description of what he did.
Bob
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Re: Bob's Super Simple 4th Axis

Postby flying_flip » Thu Mar 30, 2017 9:34 pm

Bob,

Great design and I would love to try it. The smallest bit I have is 1/4. Do you have the rack and pinion design that will work with 1/4 in bit? I am running a pirahna so smaller bed length.

Phil
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Re: Bob's Super Simple 4th Axis

Postby Bob » Thu Mar 30, 2017 10:11 pm

Phil,
Your .25 bit would be way too large for the detail needed when making these gears.
You should probably run some simulations with different diameter bits.
You will probably need to purchase a 1/8" diameter, or 3/32" bit for this purpose. In one of the posts, I mentioned the bit I used. This would be a good place to start.
Check with these guys: viewtopic.php?t=4832 They have been making all sorts of gears in many ways.
Another thought...While the Piranha would work well to make this device. I don't know if your machine has enough Z travel to use the device. You might have to get creative with the installation.
Bob
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Re: Bob's Super Simple 4th Axis

Postby flying_flip » Thu Mar 30, 2017 10:44 pm

I was looking to mount the rails on the side of the spoilboard (edge of the table) and therefore the gears would be lower to start the round stock would defiantly be thin, diameter 1" maybe. I will play around and see what I come up with.

Thanks
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