[Yotamkasam]

Hi,

In order to engrave and profile 1.5 mm thick aluminum sheet I tried holding it with screws to plywood base, with double stick tape to a sacrificial aluminum plate and of course with small clamps. Nothing works and in most cases (apart from the double stick tape) the sheet gets a small bend from the pressure of whatever holds it and I get uneven cuts.

Any idea what would be the best way to hold different sizes of thin aluminum or metal sheets for milling work?

Thanks!

[TarHeelTom]

Take a look at this "slim vise", built by Tryally, in Brazil.

[nomedia="http://www.youtube.com/watch?v=YsLhXwt8pX0"]YouTube - A SLIM MILLING VISE TO SHERLINE MILL "HD"[/nomedia]

Tom

[Yotamkasam]

Funny you mentioned that Tom as I posted this few days ago:

Tryally’s Slim Vise « Nino Ransenberg

Anyway, a vise is not an option for 1.5mm sheet.
Now I am trying hot glue by melting it with hot air gun.

[TarHeelTom]

Funny you mentioned that Tom as I posted this few days ago:

Tryally’s Slim Vise « Nino Ransenberg

Anyway, a vise is not an option for 1.5mm sheet.
Now I am trying hot glue by melting it with hot air gun.

I've never used it, but would think that double stick tape would be the best method. I see it recommended often by a couple of gurus.

Gotta love Tryally. I built his slim vise, but built it somewhat bigger. Then after trying to use it, I cut it down to his original size. My bigger version wouldn't fit on the Sherline table very well. He seems to have a lot of things thought out very well.

Tom

[diyengineer]

CNC Pressure Foot Clamping Attachment - Clamp and Cut Parts on Your CNC Machine Without Using Tabs or Double-Sided Tape - WidgetWorks Unlimited

They used that to cut out .010" aluminum.

[awerby]

a vacuum pod. That's a sort of tray that you can hold down to the bed of the mill, then use a low-pressure/high-volume vacuum pump to energize; it sucks the metal down and lets go when the vac's released - no gummy mess to clean up afterwards. Here's a link to a deluxe one which makes vacuum from shop air (but you can make your own, especially if you've already got a vacuum pump):

VT1010

Andrew Werby
ComputerSculpture.com — Home Page for Discount Hardware & Software

[HelicopterJohn]

Hi,

Use a vacuum pump and make your own fixture plate with gasketing material.

I have used this method for engraving thin sheets of plexiglas with good success.

[Yotamkasam]

I will look it up.

[TarHeelTom]

Hi,

Use a vacuum pump and make your own fixture plate with gasketing material.

Can you clarify this method for us, perhaps even with a picture or two....

thanks

Tom

[LeeWay]

This is what I use.
I ground the toggle clamps to a point, so they can hold the sheet without a lot of force. They just dig in a bit. The backing plate I use is just some black paper type phenolic. It takes coolant well and provides a flat stable base for cutting.
[nomedia="http://www.youtube.com/watch?v=fswDGVjeZPc"]YouTube - Milling aluminum sheet[/nomedia]

[miljnor]

Low temperature wax works extremely well on thin sheets too. you have to make a plate to wax it too so that you can have it out of the machine for heating....then set it in the hot sun (provided your location allows this) or an oven or torch (worst method) and I would think hot lamps would work too.

I've have only done relatively small pieces and these can bet but in ovens at home if necessary but the sun is what I've used in the past.

also used double stick tape and a special super thin tape the machinery tool sales people ....sale....lol.... Don't care for this method as much because of clean up. (although wax is a bit messy it doesn't warp the part badly)

[HelicopterJohn]

Hi Tom,

Here is a quick link to show you how I use a vacuum fixture plate for engraving on my HAAS TM-1P CNC Tool Room Mill.

[nomedia="http://www.youtube.com/watch?v=7zB7dbO9pFo"]YouTube - Vacuum Fixture Plate.wmv[/nomedia]

I made the fixture plate from 1/2 thick Plexiglas. The center hole i.e. vacuum source was tapped with 1/8" Pipe Tap and used (heavy wall 3/8" I.D. hose) so it doesn't collapse when vacuum is applied. I cut a couple of pieces of aluminum and drilled and tapped them into the bottom side of the Plexiglas fixture plate so I could grip them with the vise jaws. The I cut 1/8" deep channels in the top of the vacuum plate to allow the vacuum to reach all the way to the inside edge of the gasketing material. I purchased the Gasketing Material from Allstar Adhesive Products. I used the Low Density 1/4" wide by 1/4" thick gasket material. They recommend cutting the slot 3/16" deep for the 1/4" material to allow for compression of the gasket material. I cut the slot slightly wider than 1/4" because the gasket material has adhesive on the bottom edge and tends to try and stick to the inner sides of the slot during installation. NOTE: THE GASKET MATERIAL IS NOT COOLANT PROOF

John

[diyengineer]

Thats pretty slick! Prolly a silly question but ill ask anyways, Say you wanted to engrave on a 12"x12" piece of aluminum. How do you ensure the piece of aluminum is "square" on the vacuum vise? Or else your engraving wouldn't be straight ya know? I'm sure its easy to just, just always wondered how. I'm a noob.

Hi Tom,

Here is a quick link to show you how I use a vacuum fixture plate for engraving on my HAAS TM-1P CNC Tool Room Mill.

YouTube - Vacuum Fixture Plate.wmv

I made the fixture plate from 1/2 thick Plexiglas. The center hole i.e. vacuum source was tapped with 1/8" Pipe Tap and used (heavy wall 3/8" I.D. hose) so it doesn't collapse when vacuum is applied. I cut a couple of pieces of aluminum and drilled and tapped them into the bottom side of the Plexiglas fixture plate so I could grip them with the vise jaws. The I cut 1/8" deep channels in the top of the vacuum plate to allow the vacuum to reach all the way to the inside edge of the gasketing material. I purchased the Gasketing Material from Allstar Adhesive Products. I used the Low Density 1/4" wide by 1/4" thick gasket material. They recommend cutting the slot 3/16" deep for the 1/4" material to allow for compression of the gasket material. I cut the slot slightly wider than 1/4" because the gasket material has adhesive on the bottom edge and tends to try and stick to the inner sides of the slot during installation. NOTE: THE GASKET MATERIAL IS NOT COOLANT PROOF

John

[HelicopterJohn]

Hi diyengineer,

That particular fixture was made so that the engraving is done and then the outside edge is cut in the second operation of the CNC program. The plexiglas sheet is rough cut slightly oversize so when all the cutting is done the outer edges are square.

If I had the plates precut to size with finished edges I would have put a couple of location pins in both the X and Y axis so when you placed the material on the vacuum fixture plate it would automatically align it (say when you pushed it into the upper left hand corner.) I would then reference work offset off one corner of the part as drawn in my ONECNC CAD/CAM program.

I just purchased a Shopbot PRT 48" X 96" CNC Router and intend to make some vacuum fixture plates for it as well. The vacuum fixture plates are easy to make and they will hold small parts as well as large ones.

Hope you enjoyed the video.

John

[TarHeelTom]

Hi Tom,

Here is a quick link to show you how I use a vacuum fixture plate for engraving on my HAAS TM-1P CNC Tool Room Mill.

YouTube - Vacuum Fixture Plate.wmv

John

Nice work, John.

Tom

[HelicopterJohn]

Hi,

I have attached a few pictures of a prototype vacuum fixture plate I made for my ShopBot Router.

First I Home Referenced the machine and then drilled a series of holes in both the X and Y Axis. These holes are 1/4" in diameter. The holes were offset a distance that would put the edge of the 1/4" delrin removable pins in alignment with the edge of the material that is placed on the table. Then I placed the fixture material on the table and countersunk a series of holes on the outer perimeter and screwed it down to the table with drywall screws.

Then I surfaced the plywood fixture plate and cut the groove for the vacuum tape slot, associated vacuum slots and vacuum input port. I then removed the plywood fixture and drilled a 1/4" vacuum input port hole all the way through to the vacuum port vertical hole that was machined into the fixture. Then I drilled a larger hole that was slightly undersize of the flexible plastic air line and press fit it into the side of the vacuum fixture. I could have drilled those holes prior to machining the face of the plywood fixture plate. I use a Gast Vacuum Pump to hold the Plexiglas Sheets to the Vacuum Fixture for machining.

I will make a You Tube video after I get the process finalized.

Enjoy!

John

[diyengineer]

Awesome! Can't wait to see the video!!

Hi,

I have attached a few pictures of a prototype vacuum fixture plate I made for my ShopBot Router.

First I Home Referenced the machine and then drilled a series of holes in both the X and Y Axis. These holes are 1/4" in diameter. The holes were offset a distance that would put the edge of the 1/4" delrin removable pins in alignment with the edge of the material that is placed on the table. Then I placed the fixture material on the table and countersunk a series of holes on the outer perimeter and screwed it down to the table with drywall screws.

Then I surfaced the plywood fixture plate and cut the groove for the vacuum tape slot, associated vacuum slots and vacuum input port. I then removed the plywood fixture and drilled a 1/4" vacuum input port hole all the way through to the vacuum port vertical hole that was machined into the fixture. Then I drilled a larger hole that was slightly undersize of the flexible plastic air line and press fix it into the side of the vacuum fixture. I could have drilled those holes prior to machining the face of the plywood fixture plate. I use a Gast Vacuum Pump to hold the Plexiglas Sheets to the Vacuum Fixture for machining.

I will make a You Tube video after I get the process finalized.

Enjoy!

John