Model Railroading > Styrene Milling advice / milling bit recommendations

So I bought a drill press and XY table from Proxxon for my Proxxon rotary tool (dremel clone). My intention was mostly for milling and drilling styrene models when kitbashing. 

Works well as a drill press.. 

Milling, I am running into the the bits clogging with melted plastic. They start cutting clean, but as the plastic accumulates on the bit it melts, and then the cut edges start to melt. 
The generic tiny ones that I bought on Amazon were horrible... The Dremel mill bit works much better, but its huge at 3/8 inch. 

Anyone have any recommendations on milling bits, or does the rotary took just go to fast? 

Thanks in advance!
 

The rotary tool is turning much to fast, see if you can find/get a rheostat the will slow the tool down, I've heard of them being made out of old sewing machines parts but I'm sure you can purchase one.
   Try Google  and see what you find also I would look at a tool shop that sells good quality milling bits as they tend to be much 'sharper' than the Amazon ones.
  Check out Micro Mark they may have what you need, kctools.com may also have what you need.

   Malcolm
 New Zealand.

And if you turn the speed down to much the flutes will want to catch on the workpiece and want to twist it.

Quite honestly, depending on what you're doing, I would just use files and do the work by hand. Mabey use the mill or rotary tool to make big cuts like cutting a shell in half, but I wouldn't use it for fine work.

Posted from Android

Doug Wetherhold
Macungie, PA

Spray a bit of wd-40, keep the fast spindle speed and take smaller cuts.

ALCO630 Wrote:
-------------------------------------------------------
> And if you turn the speed down to much the flutes
> will want to catch on the work piece and want to
> twist it.
>
> Quite honestly, depending on what you're doing, I
> would just use files and do the work by hand.
> Maybe use the mill or rotary tool to make big cuts
> like cutting a shell in half, but I wouldn't use
> it for fine work.
>
> Posted from Android

If its doing that there are several reasons, too slow, wrong mill bit, too deep a cut, wrong tool turning the bit as in has not torque, material wrong for milling as in too soft. Just some of the things that can happen and I don't use a dremmel style tool they do not have enough torque. I use my Rockwell Knee mill for most things. Yes its a small full sized mill and if I only had a Bridgeport would use it may sound like over kill but they work just fine and save buying two mills one small actual bench mounted milling machine and another for my full sized milling needs. Trying to use items that are really not made for that use is a waste of time and material along with being very frustrating same with a trammel drill press.  Just what I have found over the years being  a modeler and a mechanic I also model in 1.5" scale railroading.  Boyd in Chiloquin OR home of Train Mountain.

Thyen only time I used a Dremel, etc., on styrene is on big spaces away from edges, like windows... And used it slowly and wth caution!

Bill Deaver
Tehachapi, CA

If you have a plastics supplier near by, they can recommend correct tooling, drill bits for plastic have a differently ground tip so it won’t grab the plastic. Running the drill bit in reverse helps some what, but takes longer and patients. I tried this back in the mid70’s on Athearn  diesel shells, then Atlas, to remove dynamic brake blisters and cooling fans. Dremel motors have way too much rpm, motor speed control needed. Special milling bits needed with correct cutting pitch and rpm.water cooling or recommended cooling cutting fluids. Putting wooden blocks inside shells stops vibrations and “chatter” that makes cutting difficult. I’m sure things have progressed since the 1970’s !  Wish I could recommend more.
CM80.46. I’m a dinosaur.

I agree with you Bill have ruined more than one item when the tool some how moved to where it was not wanted. Must have been one of those CA earthquake moments up in WA state. LOL

"Speeds and Feeds"
That is what my machine shop class pounded in to our heads.  The Speed (RPM) of the bit, and the Feed rate of the material into the bit.  Both will affect the quality of the cut.
A mill has precise control of RPM.  I assume the X-Y table is manual, but if there is a  variable auto-feed, then that is the hot set-up.  Adjust both to accomodate the material and type of bit.

Since the material being cut is plastic, one additonal issue is heat.  Keeping the bit cool is important or it will merely melt the shavings and eventually ball-up. But what can be used as a coolant?

Air - 
It is not as good at heat transfer as a liquid, but it will keep the chips away from the cut.  It doesn't contaminate the plastic with chemicals.

Water - 
Great at heat transfer, but not so good for steel bits, or steel X-Y tables since they will rust.  Water will be everywhere.

Coolant - 
A chemical that has a rust inhibitor, added to water.  Better for steel, but may contaminate the plastic (so paint or glue won't adhere as well).  The part will require careful cleaning to remove any residue.

MMD Wrote:
-------------------------------------------------------
> The rotary tool is turning much to fast, see if
> you can find/get a rheostat the will slow the tool
> down, I've heard of them being made out of old
> sewing machines parts but I'm sure you can
> purchase one.

Motors are usually cooled by a fan connected to the motor shaft that may only provide enough cooling over a certain speed range of the motor. If you add a rheostat then you need to make sure neither the tool nor rheostat overheat. You will probably also void the warranty.