Drilling through plexi

[trents]

Use gentle, intermittent pressure when drilling. Push and then retract. Pause. Then drill some more. That will help keep heat down. Patience is critical. One melted or cracked bore will cost you a whole plexi panel.

If you can't reduce the rpm of the drill like you would want, find some kind of 120v rheostat device to reduce the voltage to the drill.

http://www.ebay.com/itm/AC-120V-15A...505908?hash=item488d5fb874:g:QzAAAOSwdGFY0qQt

 

[Dopa]

Use gentle, intermittent pressure when drilling. Push and then retract. Pause. Then drill some more. That will help keep heat down. Patience is critical. One melted or cracked bore will cost you a whole plexi panel.

If you can't reduce the rpm of the drill like you would want, find some kind of 120v rheostat device to reduce the voltage to the drill.

http://www.ebay.com/itm/AC-120V-15A...505908?hash=item488d5fb874:g:QzAAAOSwdGFY0qQt

Will be mask taping the edges and might as well use water while drilling to actively reduce the temps.. I might be able to reduce the RPM by getting the belts hooked on the pulleys with the smallest radius of them all. Will see how fast it is then and I might order the rheostat.. getting all the required tools is a challenge as well.

 

[trents]

Keep us posted.

 

[Dopa]

So an update.. I did some research and there are two kind of taps I can use. Spiral flute and bottoming tap. Spiral flute is kinda better for blind holes but the bottoming tap does the job pretty well. I'm ordering a 2.5mm cobalt drill bit but I can find a plexi specific drill bit that doesn't melt or crack the plexi. I was also thinking of countersinking the holes I will be doing and I found a zero flute countersink drill bit for it. I will add links below. What do you think about the above? Which bits should I pick?Thanks a lot!
P.S Pics are coming soon!

Spiral Flute tap: https://www.amazon.com/KKmoon-Nitri...d=1506416063&sr=8-3&keywords=spiral+flute+tap
Zero flute countersink drill bit:https://www.amazon.com/KEO-53512-Si...16172&sr=1-1&keywords=zero+flute+countersinks
Bottoming tap: https://www.amazon.com/Irwin-Tools-...&qid=1506416219&sr=1-3&keywords=bottoming+tap

 

[Alaric]

Other than the fact that the spiral taps are metric and the regular taps are SAE, both should work, but for totally different screws. A bottoming tap is just for threading all the way to the bottom of a blind hole.

find a plexi specific drill bit that doesn't melt or crack the plexi

Drill speed is responsible for both of those. Too slow risks cracking, too fast will melt it regardless of drill type. The first can be mitigated by using sharp (new) drill bits and not forcing the cut. Let the bit cut and don't force the bit through the material.

 

[Dopa]

Other than the fact that the spiral taps are metric and the regular taps are SAE, both should work, but for totally different screws. A bottoming tap is just for threading all the way to the bottom of a blind hole.



Drill speed is responsible for both of those. Too slow risks cracking, too fast will melt it regardless of drill type. The first can be mitigated by using sharp (new) drill bits and not forcing the cut. Let the bit cut and don't force the bit through the material.

Alright then.. I thought that the spira flute tap thread would be just fine for the same screw as the normal tap. Good to know it doesn't. What about the countersink drill bit? Did you have any experience with that and plexi?

 

[Alaric]

I usually countersink with a larger drill bit, or one like this https://www.amazon.com/Bosch-CST1-T...id=1506418404&sr=8-3&keywords=countersink+bit It looks like a good idea but I haven't used that type before. Either of those tap types would work, you just have to match the threads to the screws you're using.

 

[Dopa]

I usually countersink with a larger drill bit, or one like this https://www.amazon.com/Bosch-CST1-T...id=1506418404&sr=8-3&keywords=countersink+bit It looks like a good idea but I haven't used that type before. Either of those tap types would work, you just have to match the threads to the screws you're using.

Ok cool.. I will get a zero flute then as it seems better for plexi.. less chance of chipping or cracking at any speed and I will be getting this set of taps: https://www.amazon.com/gp/product/B003K15EQG/ref=ox_sc_act_title_2?smid=ATVPDKIKX0DER&psc=1
Their quality seems good. What do u think?

 

[Robert17]

It seems to me that we may be now discussing an engineering issue. If you intend to tap the plexi-glass with screw threads you intend to put a screw into the effort. Which begs the question: what are the load requirements? If you are going to attach anything to plexi-glass you are going to be counting on the plexi-glass to bear the load which isn't a good idea as the plexi-glass is quite weak, not intended to bear loads as I've gleaned from the last few posts. You should consider a sandwich attachment, i.e., a brace using metal on both faces of the plexi-glass with a fastener run through the three components. If you intend to use this as a hinged panel, you'll be grossly disappointed in the half-life of your efforts without proper bracing.

 

[bob4933]

extruded plexi works well with an offset, low tooth blade and HIGH speed on the saw. If you want a finer finish on the cut, get a higher tpi blade and cut a tad slower. If you're melting plexi, your tpi is too high.

Drilling plexi with a high angle bit (aka one you'd get at a hardware store) will induce a lot of stress into the plastic and potentially cause it to crack. Lower angle bits can solve that issue, but are a bit of a novelty item. Using a coolant (water works for this) will prevent it from melting. That being said, thats more on the lines of "ideal scenario". I routinely use makrolon and lexan at work, and I really dont have much fuss drilling 3-8mm holes with "normal" drill bits.

Finally, obviously with plexiglass, you have a limited life span of how many times you can use a screw. Consider using a machine insert or keensert to greatly improve longevity in that regard.

 

[maxfly]

i completely forgot about Navigs test benches. he has a section in his new how to thread that covers plexi/acrylic drilling if i remember correctly. i would definitely hit him up and see what kind of tips he can offer. here is his how to guide.

http://www.overclockers.com/forums/showthread.php/772899-Buidling-a-Benching-Station-Navig-Style

 

[Dopa]

Thank you all for the info.. As a matter of fact, I will be mounting the mobo tray on the plexi part I'm designing so the weight of a mobo + gpu + everything on the mobo will be on that part of plexi. Do you think 10mm thick plexi will bend over time to that weight? I will contact Navigs to ask for his opinion on drill bits and possible countersink of the plexi.

 

[Robert17]

Remember that you have heat generated by the MB that must be dissipated. Plexi will not absorb heat at the same rate as sheet metal, in fact may act more like an insulator. Be sure to adequately ventilate the relief between the MB and plexi.

 

[Dopa]

Remember that you have heat generated by the MB that must be dissipated. Plexi will not absorb heat at the same rate as sheet metal, in fact may act more like an insulator. Be sure to adequately ventilate the relief between the MB and plexi.

I will be designing the back of the case in such way so that some of the airflow can pass under the mobo and cool it. I will be watercooling the rest of the parts, might go for a monoblock as I plan to get a mini ITX board on it.. DOn't know yet.

 

[trents]

What's your time frame for this project? It's been in discussion for some time now.

 

[Dopa]

What's your time frame for this project? It's been in discussion for some time now.

Well, I will be starting a friend's project with some plexi part in about ten days and then I will start mine in about 1 month. Just prepping everything so that I don't get caught by surprise.. I will order the tools right now and probably a piece of 10mm plexi to start practising on it. I did find a tap set by Irwin Tools: https://www.amazon.com/gp/product/B003K15EQG/ref=ox_sc_act_title_1?smid=ATVPDKIKX0DER&psc=1

I also found this zero flute countersink bit: https://www.amazon.com/gp/product/B00947BQ08/ref=ox_sc_act_title_2?smid=ATVPDKIKX0DER&psc=1 and I will be picking up 2 bosch cobalt drill bits one for the plexi parts one for the metal parts.

 

[trents]

Good plan. You can learn from your mistakes helping your friend before you start yours.