UHMW Feeds/Speeds finish

[donek]

I've been using an accupro 1/4in upcut (MSC part: 71177943) for machining UHMW. I have produced a number of prototypes cutting at 2.5in/sec and full speed on the router. Side milling looks great, but surface cuts are not great and there's always flash or fuzz at the edge of a flat and side milled surface.

Back when I use to cut snowboard bases with a router, the best way to avoid such a problem was to push the router as fast as possible. It occurs to me that this is likely a solution, but I'm not certain how fast I can safely feed with the standard. OR how slow I can turn the router and still feed successfully. There's likely an ideal router speed and feed speed. A little experimenting would likely find it, but I thought I'd ask if anyone here has experience with this material. Perhaps there's a better cutter for the job.

[steve_g]

Sean

Every manufacture has their own chip load charts... looks like Onsrud recommends chiploads anywhere from .006 - .012 per flute for 1/4" bits in plastic.

Steve

[donek]

Sean

Every manufacture has their own chip load charts... looks like Onsrud recommends chiploads anywhere from .006 - .012 per flute for 1/4" bits in plastic.

Steve

I'm actually unable to access the documents on their web site regarding recommended chip load(http://www.onsrud.com/plusdocs/Doc/index.html?model.code=FeedSpeeds). Is this number for soft plastics? As I suspected, it indicates I need to drop my rpm or feed faster.

[steve_g]

Sean

Yes, this is the range various 1/4" bits have under the soft plastics. This is likely a good enough STARTING point to figure out what's best for your situation. Would you like me to scan that page of my catalog and e-mail it to you?

Steve

[knight_toolworks]

The biggest problem I have with it is staying down and the shavings jamming things up. I have to use tabs or an onion skin to keep it on the table even in larger pieces. still better then the one time I cut acetel. that was a warping nightmare.

[jim_vv]

Greetings,

Another great source for feeds and speeds for cutting plastics is Onsrud's Plastic Routing Site (http://www.plasticrouting.com/index.html) . Click on the Router Bit Search tab and then you can search by material type, brand name, or company. If you don't use Onsrud cutters, just find one that matches your cutter's geometry. It will be a good start.

Kind regards,

JIM

[steve_g]

Onsrud has no end of helpful info... they just seem to have a problem with their web hosting. It's often slooooow or down. I've mentioned this to them, and anyone else with the opportunity should do the same!

Steve

[garyb]

Steve, Onsrud changed their servers a month ago,which resolved the slow connections.
if your using a bookmark link to access, delete it and redo your bookmark.
Gary

[steve_g]

"redo your bookmark"


Thanks Gary!

Steve:)

[donek]

Sean

Yes, this is the range various 1/4" bits have under the soft plastics. This is likely a good enough STARTING point to figure out what's best for your situation. Would you like me to scan that page of my catalog and e-mail it to you?

Steve

That would be great.


The biggest problem I have with it is staying down and the shavings jamming things up. I have to use tabs or an onion skin to keep it on the table even in larger pieces. still better then the one time I cut acetel. that was a warping nightmare.

I've cut both. Maybe my vacuum setup is different, but I never had any problem with it moving on the table as long as the blanks are a couple of square feet. I never cut all the way through though. I just use a laminate trim bit on a router table to cut the last 0.030.


Greetings,

Another great source for feeds and speeds for cutting plastics is Onsrud's Plastic Routing Site (http://www.plasticrouting.com/index.html) . Click on the Router Bit Search tab and then you can search by material type, brand name, or company. If you don't use Onsrud cutters, just find one that matches your cutter's geometry. It will be a good start.

Kind regards,

JIM

This is interesting. It suggests a 3/4in depth of cut on a single flute 1/4in spiral up cut at 100 ipm. That's at the bottom end of the chip load mentioned earlier. I can see a bit of trouble keeping the material in place at that depth of cut. I've been running a max depth of cut of 1/4in.

I may try to max out the chip load on a very shallow cut to produce a clean corner and then go deeper at a lower feed rate. Looks like I have another round of prototyping on this new product.

[knight_toolworks]

T
I've cut both. Maybe my vacuum setup is different, but I never had any problem with it moving on the table as long as the blanks are a couple of square feet. I never cut all the way through though. I just use a laminate trim bit on a router table to cut the last 0.030.
.
that's what I meant cut through and you are doomed. I usualy cut through most things and learned that lesson the hard way.

[steve_g]

Sean

Somehow I missed your request for a scan of the chipload chart... hope you can still use it

Steve





Right click on thumbnail... select "open link" the + click makes it usable on my screen ...Steve

[donek]

Sean

Somehow I missed your request for a scan of the chipload chart... hope you can still use it

Steve





Right click on thumbnail... select "open link" the + click makes it usable on my screen ...Steve

thanks steve

[gundog]

I have come to the conclusion UHMW does not cut great on a SB. I cut a lot of it, if I need a nice finish I do that as a second operation on another machine a lathe or saw.

I cut a 4" round roller type piece about once a month 100 or more at a time in 1.25" thick material. I cut these parts over size by .150" and put them on a mandrel and stack 10 at a time on the mandrel then take them to my metal lathe and finish them in one pass. I cut other parts from UHMW that the edge isn't that important and use them straight off the SB. I use Forest no melt saw blades and they leave a nice finish.

I have learned a few things cutting the material on a lathe. It needs a heavy cut and slow and it peels like an apple. I take a faster finish cut but nothing approaching router speeds and the machine is more rigid.

I made some parts on my CNC milling machine using the same bits I use on my router and the finish was great but I cut them at a slower RPM and the mill is a 4000# machine with servo motors.

The SB cuts the parts it just doesn't make a nice edge finish it has a lot of chatter marks. I have tried many different bits and speeds and feeds if you find something that works please share I have been doing it for about 4 or 5 years.

The anchor roller below are where I use these parts the rear cradle has a chattered finish but it is not real important. The side rollers are the parts I was talking about. The center roller is cut manually in a metal lathe I take the large v cut out after I have cut the center groove with a custom ground bit I made the V is then cut into the part one side at a time in 2 or 3 rough cuts and one finish pass. If the finish pass is too light it looks terrible you need to remove at least .070" then is shines like a new penny. If you try and cut it with a light pass under .050 it looks bad with a lot of hairs. UHMW is funny stuff to work with.

I make other parts from Seaboard® a type of HDPE and it machines much better in the SB. The Seaboard® is more brittle the UHMW has to be used on some parts so it is just something I have to do.

Before I bought the SB I had these parts made by a shop with a $100,000 router with tool changer and it left a chattered finish also. I really think you have to turn slower than a router with a heavy feed to get a good finish IMHO.

Mike

[knight_toolworks]

part of it too is the material is grabby like polycarbonate. so it really creates the chatter on the shopbot.

[donek]

I have come to the conclusion UHMW does not cut great on a SB. I cut a lot of it, if I need a nice finish I do that as a second operation on another machine a lathe or saw.

I cut a 4" round roller type piece about once a month 100 or more at a time in 1.25" thick material. I cut these parts over size by .150" and put them on a mandrel and stack 10 at a time on the mandrel then take them to my metal lathe and finish them in one pass. I cut other parts from UHMW that the edge isn't that important and use them straight off the SB. I use Forest no melt saw blades and they leave a nice finish.

I have learned a few things cutting the material on a lathe. It needs a heavy cut and slow and it peels like an apple. I take a faster finish cut but nothing approaching router speeds and the machine is more rigid.

I made some parts on my CNC milling machine using the same bits I use on my router and the finish was great but I cut them at a slower RPM and the mill is a 4000# machine with servo motors.

The SB cuts the parts it just doesn't make a nice edge finish it has a lot of chatter marks. I have tried many different bits and speeds and feeds if you find something that works please share I have been doing it for about 4 or 5 years.

The anchor roller below are where I use these parts the rear cradle has a chattered finish but it is not real important. The side rollers are the parts I was talking about. The center roller is cut manually in a metal lathe I take the large v cut out after I have cut the center groove with a custom ground bit I made the V is then cut into the part one side at a time in 2 or 3 rough cuts and one finish pass. If the finish pass is too light it looks terrible you need to remove at least .070" then is shines like a new penny. If you try and cut it with a light pass under .050 it looks bad with a lot of hairs. UHMW is funny stuff to work with.

I make other parts from Seaboard® a type of HDPE and it machines much better in the SB. The Seaboard® is more brittle the UHMW has to be used on some parts so it is just something I have to do.

Before I bought the SB I had these parts made by a shop with a $100,000 router with tool changer and it left a chattered finish also. I really think you have to turn slower than a router with a heavy feed to get a good finish IMHO.

Mike

Thanks for all the details mike.