CNC Edge bender

For discussions related to designing and making ski/snowboard-building equipment, such as presses, core profilers, edge benders, etc.

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Buuk
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CNC Edge bender

Post by Buuk »

I did recently build my first CNC edge bender...

Image

It's still a beta version and needs some important updates to improve it, however it seems to work great :)

To optimize this design I will post some discussion points later today...

Buuk
Make things as simple as possible, but not too simple

skidesmond
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Post by skidesmond »

Wow! I'd love to see this in action.

OAC
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Post by OAC »

Ha ha! (That's an impressive laughter!) :D
No further comments, other than: I want one!, the picture speaks for it self!

Buuk
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Post by Buuk »

I would like the opinion of you guys on the following situation.

Assuming we want to bend a radius of 40mm (without relapse) I would like to sketch four situations.

Drawing 1, the current situation. The two bottom rollers have 120mm between the centres (caused by belt pulleys) and the centre roll needs to move down pretty far to create a bend. This puts a lot of stress on the entire system. And needs lot of friction to feed the edge through the system

Drawing 2 and 3 show a reduces distance between the two bottom rollers. As we see, it looks like the smaller this distance, the less force is needed to feed the edge through. This can be obtained by placing the gear pulleys at a different height level.

Drawing 4 has the two bottom rollers close to each other and also a smaller diameter of these rollers. As these rollers are powered, the less radius means more force will be generated.

There should be an optimal situation somewhere…. Your feedback is very welcome!

Thanks in advance,

Buuk

Image
Make things as simple as possible, but not too simple

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threeninethree
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Post by threeninethree »

Been thinking of this also but I havent gotten close to your stage.

Could you have a separate feed assembly like this:
(its just a rough idea)
Image
~ Matt

twizzstyle
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Post by twizzstyle »

Wow, that is amazing, very nice work. I've been toying with the idea of putting a stepper on my edge bender for a while. I'm already running my mill with CNC.

The biggest thing I've worried about is feeding the edge. Since it's not a closed-loop system, if the edge slips at all you're basically hosed.

Buuk
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Post by Buuk »

I think that feeding the edge is indeed one of the problems we have to solve. However, the edge was feed through as long I did not bend the edge too much. So changing the geometry will maybe solve this problem. The two bottom rollers which are powered can deliver a torque of about 12Nm so quite a lot.

Another idea is to cut the groove in the bottom rollers a few millimeters deeper than needed and put a rubber ring in here to obtain more grip on the edge. However, this will make it probably even harder to estimate the bending parameters.

During the next weeks I hope to find some time to change the roller position and perform some new tests. I will keep you updated!


Buuk
Make things as simple as possible, but not too simple

twizzstyle
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Post by twizzstyle »

This is great, I'm going to keep a close eye on this thread, this will likely inspire me to CNC my bender :)

The problem I see with a feed roller on the side is that as the center die moves inward to tighten the bend radius, the un-bent edge material being fed in comes in at a completely different angle. The feed roller would have to move side to side (a large amount!) to account for the variable feed-angle-vs-bend-radius.

One thing I've thought about is tiny "teeth" inside the center roller that go between the edge flange bits. Does that make sense? Almost like a chain and sprocket, except instead of a chain it is the edge, and instead of a sprocket it's the roller die. I would have to make the roller in two pieces on my CNC mill instead of the lathe, but it wouldn't be hard at all.

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Head Monkey
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Post by Head Monkey »

Awesome work… I’ve always wanted to do this, but never gotten around to it. Nice job.
Everything I know about snowboard building, almost: MonkeyWiki, a guide to snowboard construction
Free open source ski and snowboard CADCAM: MonkeyCAM, snoCAD-X

strangesnowboarding
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Post by strangesnowboarding »

great work! i have seen these at work and am excited to build my own setup too!

hugocacola
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Post by hugocacola »

you stolen my idea when i was a sleep... grrrrrrrr

Awsome work dude..

Buuk
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Post by Buuk »

Finished a new prototype of the CNC edgebender this weekend with the rollers much closer to oneother. Works a lot better than the previous versions :D I will try to post a video of the bending in the next few days...

Image

Buuk
Make things as simple as possible, but not too simple

Richuk
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Post by Richuk »

Looks great - glad to here it is yielding the results you are working hard to achieve.

leboeuf
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Post by leboeuf »

Wow.... That is impressive!

Just a thought:
Could you judge your feed based on an optical sensor to look at the passing teeth? You could write your CNC code based on what tooth you are on. I'm not sure if a "tooth" of resolution would be good enough though...

Basically the same concept that the old ball computer mice used.

twizzstyle
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Post by twizzstyle »

That's not a bad idea, but like you said the resolution of "a tooth" might not be good enough.

I thought I could be clever and make a "gear" or "sprocket" of sorts that actually went in between the teeth to pull it through. It was going to be my center roller, and once I got the "sprocket" shape figured out, I could easily CNC that on my mill. But then I realized, at tight radii like on the very tip, the edge teeth actually end up touching each other, so a sprocket couldn't go between. Dang it. Plan foiled. A seperate feed sprocket would still work, but then I have to worry about the in-bound edge angle changing as the radius changes, and that's hard.

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