Cutting Cheap PlexiGlass Any Luck?

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izumi5188
Posts: 64
Joined: Mon Dec 08, 2014 7:38 pm
Location: Madison, WI

Cutting Cheap PlexiGlass Any Luck?

Post by izumi5188 » Wed Feb 11, 2015 10:10 pm

So, Despite all the "Warnings" that is really hard to cut the cheap plexiglass plastic, I had to give it a go.

I have set my surface feet per min to 450, and my chipload to .006 and it barely melts. The issue, now lies on the machine bounces during some cutting causing 0,0 not to be 0,0.

Should I back off my surface feet and increase my chipload?

Anyone have any success?
-IzumI-
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danimal
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Re: Cutting Cheap PlexiGlass Any Luck?

Post by danimal » Thu Feb 12, 2015 3:26 am

If you are seeing any melting, then you are traveling too slow or your cam software may not speed compensate in corners.

If your machine is missing steps, your load force is overcoming the stepper motors. You can increase the current through the motors (will generate more heat but will help prevent missing steps). You will probably need to add additional cooling for the GRBLshield. Or you can limit your pass depth until it stops missing steps. I would recommend a combination of the two.

I would run my current up until I could feel the steppers getting warm over the course of a job, but not too hot. Then I would balance the temperature between motors as best I could. Temperature is not the main concern, just an indication of power dissipation that the motor is seeing throughout operation. I try to keep it equal.

Pass depth is limited by machine ridigity and stepper torque. You can have all the torque in the world, but if the machine flexes it will cause the bit edge to tip and bite off way more than your calculated chip load, and that can also lead to missing steps on a machine that otherwise could get the job done.
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HPGreyling
Posts: 123
Joined: Sat Nov 15, 2014 11:37 am
Location: South Africa

Re: Cutting Cheap PlexiGlass Any Luck?

Post by HPGreyling » Thu Feb 12, 2015 10:31 am

Depends on your bit as well. Straight 2 flute , 380mm/min, plunge rate 100mm and 0.6 mm cut. All these are useless if you are using anything else than the quiet 300w spundle. But is should give you an idea Where to start

izumi5188
Posts: 64
Joined: Mon Dec 08, 2014 7:38 pm
Location: Madison, WI

Re: Cutting Cheap PlexiGlass Any Luck?

Post by izumi5188 » Thu Feb 12, 2015 5:45 pm

Thanks for your thoughts and suggestions.
I am using BobCad and cutting conditions are set in Surface Feet / Min (speed) and inch/tooth (chipload).
I have the quiet cut spindle, but my speed control blew (by my stupidity, waiting for a new one). So I am running at full speed, I can't cut the spindle speed down yet to try and reduce heat that way.

With that being said, do you think I should lower my speed and increase my chipload?
-IzumI-
Shapeoko 2 : With Works Kit and 1000mm Expansion
Upgrade with X-Carve, Acme Screw kit, and X-Controller

HPGreyling
Posts: 123
Joined: Sat Nov 15, 2014 11:37 am
Location: South Africa

Re: Cutting Cheap PlexiGlass Any Luck?

Post by HPGreyling » Thu Feb 12, 2015 7:34 pm

I should have also included I ran the spindle at about 30-50% of its max speed.

izumi5188
Posts: 64
Joined: Mon Dec 08, 2014 7:38 pm
Location: Madison, WI

Re: Cutting Cheap PlexiGlass Any Luck?

Post by izumi5188 » Thu Feb 12, 2015 7:35 pm

Thanks,
I will have to put this project on hold while I wait for my new speed controller then.
-IzumI-
Shapeoko 2 : With Works Kit and 1000mm Expansion
Upgrade with X-Carve, Acme Screw kit, and X-Controller

clockit
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Re: Cutting Cheap PlexiGlass Any Luck?

Post by clockit » Fri Feb 13, 2015 12:49 am

I have the Makita router and have cut the cheap/crappy box store plexi with decent results, however I do seem to get some build up on my bit from time to time... Anyway, here is what I used for settings... feed: 40"/min plunge: 11"/min depth: .040" rpm: 18,000 rpm
Shapeoko 2, Full Kit #7071, Makita RT0701C Router, 1000 x 1000 upgrade, Acme Z Axis w/Nema 17 Belt Drive

izumi5188
Posts: 64
Joined: Mon Dec 08, 2014 7:38 pm
Location: Madison, WI

Re: Cutting Cheap PlexiGlass Any Luck?

Post by izumi5188 » Fri Feb 13, 2015 2:46 am

Thanks clockit!
I will give that a try as soon as I get my new speed controller.
-IzumI-
Shapeoko 2 : With Works Kit and 1000mm Expansion
Upgrade with X-Carve, Acme Screw kit, and X-Controller

cyberreefguru
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Cutting Cheap PlexiGlass Any Luck?

Post by cyberreefguru » Sat Feb 14, 2015 11:11 pm

I've found a very low RPM setting makes a huge difference when cutting ABS. I would think the same applies to plexiglass. If I go above 2.5 on the stock dremel I see melting. I have no clue what the actual RPMs are. That's with feed rate of 12 and plunge rate of 7. I'm issuing a .125 or .0625 2 flute bit. Plexi is on my todo list so I might have more relevant data in the future.

Tom


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