Clever alternative to vacuum hold down

[Bob Eustace]

This rather intrigued me. A pair of air cylinders pull down the rollers onto the flat goods. Also has an intrigueing semi automatic ATC that could be adapted to our bots. I can see the hold down working as long as you had stops either end. A great solution if you cant get 3 phase power into your shop. The sheet doesnt seem to mark with the shavings.

http://www.generalcnc.ca/irouter_ultimate

http://youtu.be/NIDuz7MRGhE

[steve_g]

Bob…
Word has it that you can lease that tool changer already adapted to the bot for about $25/hr.
Techno offers a OEM Roller Hold-Down System.

SG

[srwtlc]

The sheet doesnt seem to mark with the shavings.That's because he's making 'flour' out of what ever material he's cutting! RPM a tad high maybe?!

Added benefit of increased hold down force as stuff gets built up on the rollers too. :rolleyes:

[Ajcoholic]

At the IWF I saw a large, moving table CNC router with a similar roller hold down assist. Each roller was on its own set of pneumatic cylinders.

My mind was already thinking how to rig a similar setup on my Buddy :)

That General CNC needs a dust collector.. badly!

[Kyle Stapleton]

When would you use something like this?

[scottp55]

Thanks for posting Bob, I see a lot of issues, BUT it certainly got me thinking:)
Guy used "Freestyle Script" so he can't be ALL bad:rolleyes:

[Bob Eustace]

Andrew been looking at the Buddy all arvo and the thing is just made for it as it would be a cinch to fit it on the side rails with no mods. Would give more Z than any vacuum. I think it would solve Mikes current HP dilemma. Did you notice the 1/16 radius in the cut out with the 1/4 as the single pass bit? Would love that tool change idea - ticks all the boxes for small operators dont you think. On the dust it probably has collection but just off for the video - there is a ton of room there for a Kent.

[Simops]

Interesting hold down Bob......for flat sheet stock it certainly seems to work well and less noisy I bet then a vac pump. Never the less as I see it only good for flat sheet and there must be quite a bit of force downwards by the rollers otherwise you would expect the piece being cut to shift, especially with higher feed rates. With vac you could still use it with some 3D cutting whereas the rollers don't think would. Anyhow not able to install 3 phase here so stick to my limited single phase solutions. :rolleyes:

The quick manual tool change is something that certainly gets my attention.....not having to do re-zeros after every tool change is real nice! I like to use a downcut bit first then finish off with upcut bit on sheet goods to get best edge finish (like it better than compression) so this quick MTC would be great.

Cheers

[Bob Eustace]

Do-able for $250 easy. Agree only good for flat and he is using end location. I too truly would kill for the tool change. Idiot proof and no more drilling a hole through to China! On load its not going to be much at all particularly if you made the roller up with several wheels like a conveyor. Sewing machines have used this idea for years and our CNC quilter certainly does. Anyway its pretty easy to make up a mock up for proof of concept. There is also a saving of cutters never hitting screws as well.

[Sk8MFG]

Echo of what most have said. Neat concept for flat stock. I bet if the spoil-board was covered in some sort of no-slip and one only did onion cuts a DIY version could work quite well.

I need more tool changers in my life...
Or at very least get around to putting a drill on my Z

[Kyle Stapleton]

The roller just hold down (in a very small area), so Wouldn't you still need to tab your parts?

[englert]

Generally, roller hold down is used for machining multiple sheets of material. A typical application is with upholstered furniture or some interior components in the RV industry.

Since the machine rollers are moving back and forth across the material, the material can shift. So roller hold down is typically not used for applications that require accuracy. Sometimes machines combine both hold down methods, i.e., vacuum and roller hold down. The vacuum of course only works on the bottom sheet, so the rollers are usually used when only one sheet is cut. Generally, these types of machines are used for higher throughput. Cut as much as you can through multiple sheets in as little time as possible.

Some considerations.

When programming, you need to try to create a tool path that works from one end to another, while minimizing the number of back and forth movements over the parts. The shortest part typically is the distance between rollers plus. The parts need to be held in place by at least one roller as it goes by. If the parts are too short, then then may just teeter-totter up and lodge or break something. You need to make sure that you have an emergency switch on the roller hold down, so that if you physically get caught under the rollers or something else happens, you can disengage the rollers and stop the machine. Also, you may not have full reach of the table with roller hold down. You do not want one roller going on and off the table. It will destroy the covering on the roller.

Just some notes on roller hold down. For most applications, vacuum is still the preferred method.

[Kyle Stapleton]

Thanks for the input.