Routing UHMW Polyethylene - Router Forums
 
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post #1 of 10 (permalink) Old 09-02-2010, 11:53 AM Thread Starter
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Default Routing UHMW Polyethylene

Hello everyone,

My name is John and I am very new to the whole "Routing World". I want to start off by thanking the community for allowing me to join this group. Thank you!!

Ok, how should I begin? I guess starting from the beginning would be my best bet. I am a downhill skateboarder and I travel at a high rate of speed..., downhill (controlled of course). I use all the necessary safety gear (ie., helmet, elbow pads, knee pads, and gloves with sliding pucks, etc.) that is necessary for my hobby. With that said, I am planning to make these sliding pucks with sheets of UHMW Polyethylene. UHMW seems to be the best material for making these pucks since it is a very tough material, with the highest impact strength, has a very low coefficient of friction, is self-lubricating, and is highly resistant to abrasion.

I would like to make these pucks in two different shapes, 3" diameter circles and
3"x3" squares with a thickness of .75". They both would have rounded edges.

So, I humbly ask the experts, what would be the right bit to cut circles and to round the edges for UHMW? Or is there a bit to do both rounding and cutting at the same time? Is there a specific jig used to cut circles from plastics? If I have to round the edges individual pieces, what would be the safest way to round the small pieces? Would I have to use a router with a certain minimum amount of horse power to cut UHMW?

Thanks for your time and consideration.

Oh, I am planning to purchase both router and table.
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post #2 of 10 (permalink) Old 09-02-2010, 12:11 PM
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Hi John

I would suggest using the Faux type bit with a template to get the round over edge you want in place and than use the hole saw to punch them out.
The UHMW is funny stuff to work with the chips will come off the router bit in strings and will lock up the router bit quick if try cut to the plug out with a router bit.

MLCS Raised Panel Carbide Tipped Router Bits 2

===

Quote:
Originally Posted by motomoto012070 View Post
Hello everyone,

My name is John and I am very new to the whole "Routing World". I want to start off by thanking the community for allowing me to join this group. Thank you!!

Ok, how should I begin? I guess starting from the beginning would be my best bet. I am a downhill skateboarder and I travel at a high rate of speed..., downhill (controlled of course). I use all the necessary safety gear (ie., helmet, elbow pads, knee pads, and gloves with sliding pucks, etc.) that is necessary for my hobby. With that said, I am planning to make these sliding pucks with sheets of UHMW Polyethylene. UHMW seems to be the best material for making these pucks since it is a very tough material, with the highest impact strength, has a very low coefficient of friction, is self-lubricating, and is highly resistant to abrasion.

I would like to make these pucks in two different shapes, 3" diameter circles and
3"x3" squares with a thickness of .75". They both would have rounded edges.

So, I humbly ask the experts, what would be the right bit to cut circles and to round the edges for UHMW? Or is there a bit to do both rounding and cutting at the same time? Is there a specific jig used to cut circles from plastics? If I have to round the edges individual pieces, what would be the safest way to round the small pieces? Would I have to use a router with a certain minimum amount of horse power to cut UHMW?

Thanks for your time and consideration.

Oh, I am planning to purchase both router and table.



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post #3 of 10 (permalink) Old 09-02-2010, 12:24 PM Thread Starter
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Thanks BJ. Sorry, but I don't know what a "Faux type bit with a template" is.
Thanks again.
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post #4 of 10 (permalink) Old 09-02-2010, 12:44 PM
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Hi John

See the link on the above post ,it's just a plunge bit that has a bearing on it to follow a template that you can make with a hole saw/jig saw//..
Once you have the round template you would drop the router in the hole and put on the edge of the disk on both sides and than the hole saw will do the rest..

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Originally Posted by motomoto012070 View Post
Thanks BJ. Sorry, but I don't know what a "Faux type bit with a template" is.
Thanks again.



"It's fine to disagree with other members as long as you respect their opinions"

Marc Sommerfeld Tools ,Videos
http://www.youtube.com/channel/UCT-n...RWaEpMA/videos

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post #5 of 10 (permalink) Old 09-02-2010, 12:47 PM
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Quote:
Originally Posted by bobj3 View Post
Hi John

I would suggest using the Faux type bit with a template to get the round over edge you want in place and than use the hole saw to punch them out.
The UHMW is funny stuff to work with the chips will come off the router bit in strings and will lock up the router bit quick if try cut to the plug out with a router bit.

MLCS Raised Panel Carbide Tipped Router Bits 2

===
Hi Bob - I like the idea but I think he will need a jig because it looks to me like he will need to come at it from both sides. I also think he would need a second operation to cut through the 3/4" with a straight bit as I don't think those bits will cut through without leaving a bead.

John Schaben

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post #6 of 10 (permalink) Old 09-02-2010, 12:54 PM
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Hi John

You don't want to use the bit to cut through the stock just used on both sides to put on the round over in place then.all done with one template..

I wouild suggest the #1719 bit,,nice round over..

====

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Originally Posted by jschaben View Post
Hi Bob - I like the idea but I think he will need a jig because it looks to me like he will need to come at it from both sides. I also think he would need a second operation to cut through the 3/4" with a straight bit as I don't think those bits will cut through without leaving a bead.



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post #7 of 10 (permalink) Old 09-02-2010, 02:29 PM Thread Starter
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Thank you gentlemen. I think I'm seeing it.
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post #8 of 10 (permalink) Old 09-11-2010, 01:59 PM
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I used to machine UHMW for use in "skids" beneath road sweepers amomngst other things, a similar (if more industrial) application in many ways. UHMW is a very "grabby" material so you need to ensure that it is well fixed down before routing it. Feeds and speeds: UHMW is best cut at a high rate of feed but reduced RPMs; we typically used to machine at a feed rate (on CNC) of 5 to 10 metres/min but with a spindle speed of just 12000 to 14000 rpm on spiral cuttres with straight (i.e. conventional) cutters feeding at 3.5 to 6 metres/min. When machining UHMW what you are looking to produce is a constant stream of curled chips rather than dust - dust indicates too high a spindle speed and/or too low a feed rate and the resulting small chips can get very hot and even fuse back on lower density grades. For any skid type application always try for the densest grad you can get. This is normally 1000 grade. Lower density grades such as 500 will work (and are cheaper) but we used to find that 350 grade was just too soft for many applications
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post #9 of 10 (permalink) Old 09-13-2010, 10:40 AM Thread Starter
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I used to machine UHMW for use in "skids" beneath road sweepers amomngst other things, a similar (if more industrial) application in many ways. UHMW is a very "grabby" material so you need to ensure that it is well fixed down before routing it. Feeds and speeds: UHMW is best cut at a high rate of feed but reduced RPMs; we typically used to machine at a feed rate (on CNC) of 5 to 10 metres/min but with a spindle speed of just 12000 to 14000 rpm on spiral cuttres with straight (i.e. conventional) cutters feeding at 3.5 to 6 metres/min. When machining UHMW what you are looking to produce is a constant stream of curled chips rather than dust - dust indicates too high a spindle speed and/or too low a feed rate and the resulting small chips can get very hot and even fuse back on lower density grades. For any skid type application always try for the densest grad you can get. This is normally 1000 grade. Lower density grades such as 500 will work (and are cheaper) but we used to find that 350 grade was just too soft for many applications
Since UHMW tends to easily catch, would it be impossible router a 1/2"x3"x3" piece of UHMW by hand with a fixed router on a table? Thanks Phil!
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post #10 of 10 (permalink) Old 09-13-2010, 03:21 PM
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Since UHMW tends to easily catch, would it be impossible router a 1/2"x3"x3" piece of UHMW by hand with a fixed router on a table? Thanks Phil!
My experience with UHMW tends me towards either cutting a shape as close as possible to finished size (bandsaw, jigsaw, etc) then taking a 1 or 2mm pass with the UHMW fixed to a heavy template to help control the process (for larger pieces) or for small pieces "onion skinning" the component within a larger sheet and then breaking out/cleaning-up with a trim router and bearing guided bit. "Onion skinning" is a procedure used in the CNC world where (multiple) components are machined on a single large sheet but instead of breaking through the material the depth of cut is 0.5mm to 1mm less than the full depth leaving all of the components held on a thin film of material. Once the main part of the machining is completed the sheet is flipped over and the onion skin sections are drilled to give clearance for the trim bit. Works well on an overhead pin router and I don't see why it wouldn't work well on an inverted router in a router table. The larger piece of material is easier and safer to handle, too

BTW I'd also suggest getting the largest router you can to do your main machining, e.g. a 2 to 3HP model with a 1/2in shank

Good luck!
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