Full Version: How do I cut plastic/metal on a rotary engraver?
From: joyce (JLADY) [#1]
29 Mar 2005
To: ALL
So far I have only burnished/diamond and engraved into plastic with regular cutters. I want to cut plastic material now on the engraver, what cutter do I need and what do I need to do different, just increase the depth until it cuts???
Thanks,
Joyce
From: Harvey only (HARVEY-ONLY) [#2]
29 Mar 2005
To: joyce (JLADY) [#1] 29 Mar 2005
If you are talking about acrylic, here are some tips.
Do not cut deep, it will tend to melt it. Set the nose to about .004 depth.
Use ACR or FLX bits. They are the same.
After using a bit on acrylic, do not attempt to use it on flex. It will do a lot of acrylic, but after a few pieces will not cut flex worth a darn.
Use a low spindle speed for best results. (Burnishing uses a very high spindle speed.)
If you are talking about profiling flex or acrylic, I will let the other experts field that, I do not do that.
From: PenTrophy (PENINSULATROPHY) [#3]
29 Mar 2005
To: joyce (JLADY) [#1] 29 Mar 2005
Joyce, Most engravers use a "sacrifice" (scrap) sheet under the sheet to be cut. This will prevent the cutter from cutting into the table or grip pad. I use a Newing-Hall Dynagrip pad and cut just into the surface with no damage to the pad's ability to grip.
http://www.antaresinc.net/FactCutterGeometry.html
This article will show you a selection of cutters available for use.
I use a parallel cutter which leaves no bevel. Then I bevel the top half of the badge/plate at 45* on a beveler.
A Profile Cutter will give you a 15-20* bevel all along the edge.
A FLX Cutter will give you a 30* bevel all along the edge.
A BAL/SSS will give to a 45* bevel all along the edge.
They make a Cutter/Beveler which is a parallel cutter with a top angle. So you just determine how deep the bevel is in the plates.
Hope this helps!
Mark
Newing-Hall Rep
In the Great Northwest!
EDITED: 29 Mar 2005 by PENINSULATROPHY
From: brokenleg [#4]
29 Mar 2005
To: PenTrophy (PENINSULATROPHY) [#3] 29 Mar 2005
From: joyce (JLADY) [#5]
29 Mar 2005
To: joyce (JLADY) [#1] 29 Mar 2005
I am assuming I can't cut sheet brass or aluminum? Am I correct??
Joyce
From: Harvey only (HARVEY-ONLY) [#6]
29 Mar 2005
To: joyce (JLADY) [#5] 29 Mar 2005
Correct!
From: Stunt Engraver (DGL) [#7]
29 Mar 2005
To: joyce (JLADY) [#5] 30 Mar 2005
Joyce,
You can cut patterns from brass or aluminum (.020-.025) sheet stock on your rotary machine, but it's hard on the cutters and there's a lot of manual cleanup, afterwards, to remove the burrs from the plate.
Even though it's technically possible, I wouldn't recommend it, unless you're in a pinch.
If you decide to try it, tape the brass/aluminum (double-face tape) to a sacrificial piece of plastic engraving stock an engrave through to the plastic piece in increments of approx. .003 (three-thousandths) of an inch per pass.
It will take a lot of passes, at slow speed, to cut the pattern. Remove the piece from the sacrificial plate and use a fine file for cleaning up the edges.
Very laborious, but possible. I occasionally make custom-sized brass ovals and disc sizes that can't be found as stock items.
It's not a service I advertise. I also sharpen my own cutters. If I didn't, I probably wouldn't cut the special shapes from brass/aluminum.
David "The Stunt Engraver" Lavaneri
DGL Engraving
Port Hueneme, CA
EDITED: 29 Mar 2005 by DGL
From: Rodney Gold (RODNEY_GOLD) [#8]
29 Mar 2005
To: joyce (JLADY) [#5] 30 Mar 2005
You can cut anything with your engraver if you have enough patience or enough power.
With small machines like the Roland with its low power spindle , you need to do whats called a multipass to cut heavier duty stuff , IE run the cut line a few times going deeper and deeper.
You need a cutter to do this , IE a bit with a cutting edge. The easiest to use is a V shaped single flute cutter which is sort of the standard engraving tool.
Stuff like engraving plastic doesnt have to be cut right thru , you can generally cut 3/4's way thru and snap stuff out , tho this generally requires de burring (clean up of the edges)
Feeds (how fast the machine travels) and speeds (how fast the motor rotates) are dependant on a lot of things , mostly the material and the cutter diameter etc , but suffice it to say that with a v shaped cutter normally used for engraving , you want to cut plastics at a high speed (IE the spindle spins fast) and high feeds. Going slow into any of the softer materials will cause problems in that you overheat the material and this leads to melting etc. Its also a good idea to use a lubricant when cutting , plastics work well with slightly soapy water and metals work well with water soluable cutting fuid obtainable at any engineering tool shop.
Most engravers should be able to cut thru 1.5mm engraving stock in a single pass with no problems whatsoever.
Various types of cutter materials are available , tungsten carbide is the best for plastics and high speed steels work best on harder metals (tungsten carbide is brittle and the cutting edge chips with hard metals and thus leads to high heat generation and worsening cutting)
You need to use a different method when cutting than dragging or burnishing, you dont really want to use a nose cone and you cannot use a spring loaded collet/bit. The cutting bit has to be as rigid as it comes , in fact the less it protrudes , the better.
The secret to cutting is chip removal and heat removal , the cutters need to have a lot of what is called back clearance so that the material used can be ejected and doesnt interfere with subsequent cutting. Coolants/lubricants can speed up cutting time and quality substantially.
Sacrificial beds can be used , but need to be leveled with respect to the engrving spindle , you use the machine itself to do it (Im not going into the exact ways in this post) , you then use a double sided tape that is sticky yet removes cleanly without leaving gum deposits (3m carpet tape works well) to hold the piece down.
Sticky mats also work with light duty stuff but have too much "give" for metals.
One of the huge advantages to a computerised rotary system is the ability to engrave and then cut , means you can do multiples without registration problems etc. If you want to do serious cutting , then the smaller systems are useless and you need something like an overhead router typee system with at least 1+ hp spindles that can go to 20 000 rpm or higher and that use vacuum type holding tables.
Hope this helps a little
From: laserman (MIKEMAC) [#9]
30 Mar 2005
To: joyce (JLADY) [#1] 30 Mar 2005
Joyce,
A little trick to setting the right depth of the cutter.
take two small pieces of the plastic to cut tape one onto the top of the other leaving 1/4 inch on the edge sort of like a step.
Hold the higher piece up against the nose cone and drop your Parallel cutter to the lower piece and tighten it.
Be sure to set your nose cone to the surface of the material and you will cut through just the single sheet of plastic.