Threading Holes

[wanareef]

I always try to find a faster way to do things and eaiser at that. Here I am threading holes in a flange for a 1/4"x20 nylon thumbscrew using a 17/64" drill bit.

All the holes are pre-drilled and then the fun begins. I chuck-up a 1/4x20 tap into my drill-driver and tap all the holes. It took me longer to write this up than it was to thread the holes.

Just a quick DIY..

 

[danno14]

Kudos on a worthwhile post! It should be noted that while this will work GREAT with smallish holes and not-thick acrylic, larger/thicker will take more.
D

 

[wanareef]

The acrylic is 3/8" thick and yes it's a small hole but will work for up to 1/2" acrylic (the max) and 3/8" thd hole

 

[kgross]

That is a great idea to use the drill/driver. I always tap by hand, but I really wish I had a tapping attachment for my drill press.

Kim

 

[wanareef]

Kim

Just chuck the tap into the drill press, with one hand on the feed and the other on the switch, this will take some practice, turn on the press start the feed and at the same time turn off the motor. I use to do this at a machine shop where I was taught to drill holes and tap them.

Takes some practice, but the drill driver is eaiser.

hth

 

[noonesname124]

Thanks for sharing.

What is that you are making? And how did you cut the big circle pieces?

 

[MC Lighting]

just a word of warning you may find that by tapping you have crazing and cracking problems down the line due to the expansion rate of the acrylic... just a thought...

 

[wanareef]

Sorry, doesn't happen. Even James @ Envision tap's his holes this way.

Have you even tried tapping holes this way and experience what your talking about or just putting something out there with nothing to back it up


noonesname124

It's a flange for a skimmer. I usually work with 6" , 8" and 10" acrylic tube's I have patterns made up and just rough cut them and trim them up on the router with a pattern bit.

 

[wanareef]

Quote:
Originally Posted by wanareef View Post
Just dry. The biggest hole is probably 3/8" and into 1/2" acrylic would be the max thickness. Always use the correct drill for the size tap.

When I use to work at a machine shop, they showed me how to drill and tap holes on the drill press (metal) Drill the hole, change out and insert the tap, start the feed into the hole, turn on the drill press and then turn it off, letting the momentum of the motor do the work.
They actually sell a device called a Tapmatic which is made for this. You chuck it up, and drive the tap through the hole then an internal clutch reverses the tap and pulls it back out, handy little tool if doing a bunch of holes.

If doing a lot of these, try a spiral fluted tap, really helps to keep the chips from packing, comes out as long threads.

As for doing it with a drill, I do it all the time, in any thickness. If the tap is good, material thickness shouldn't matter much.

Best/easiest lube IMO is a 50:50 mix of Palmolive and water. Slippery and water soluble

James

This is a quote form another board I posted and with James from Envision Plastics chiming in.

 

[MC Lighting]

yes I have and in other CNC forums found the same thing to be true if there is a indiference in material expansion it can lead to cracking. I am glad they have not had any issues and I am not saying its not alright to do it but it does take some consideration of the material and the side of the threaded hole.

 

[kgross]

Besides the issue of expansion. Threading acrylic can cause stress fractures in it. You really need to make sure you have a really good sharp tap and run it through the hole a few times. I have had pretty good luck with taping for 1/4 inch nylon screws, but a few of the first ones I did, did end up with a lot of crazying. I only ran the tap through one time, now I run the tap through at least three times to make sure the acrylic is not just flexing to allow the tap through.

Kim

 

[wanareef]

kim

What type of material was it? Extruded? I only use cast and only cast.

 

[wanareef]

yes I have and in other CNC forums found the same thing to be true if there is a indiference in material expansion it can lead to cracking. I am glad they have not had any issues and I am not saying its not alright to do it but it does take some consideration of the material and the side of the threaded hole.

You people really amaze me. I am not talking about CNC , I'm trying to share my experience of tapping holes with a drill driver. Maybe someone can benefit from this, but it's something that I have done more than once. If it didn't work, I would not put it out there. But I also mention to USE THE CORRECT pilot drill that is listed on the tap. If you don't then it's your own fault. Once you pre-drill with the listed pilot size drill then tap that hole weather by hand or other, you will not have any problems.

This will be my last post on trying to help or share with anything. I'm done.

 

[kgross]

Wanareef, I used cast.

Kim

 

[Dewi]

This will be my last post on trying to help or share with anything. I'm done.

dummy spitter

 

[matts125]

wow, thats lame!

Mc lighting wasnt even criticizing you, he just stated the obvious. I fab acrylic all the time and I know that threading holes always puts micro cracks in the acrylic, however in 99% applications that you need to thread a hole in acrylic there is no ill effects from it....

Matt

 

[Dewi]

please exuse my sarchasm - I meant no harm honest

when tapping perspex I always use my pillar drill just to hold the tap in the chuck - then turn the chuck in and out by HAND - thus ensuring the damn thing goes in straight/square - the thinner the perspex the more critical it is you stay perfectly square

 

[Saltyfish]

The only thing I would add to this is the faster you run that tap through the more friction. The more heat can cause the hole to be oval with working with acrylic.

I am not saying this is way is right or wrong. I have always said you have to find what works for you and just because it is not the way I do something does not make it wrong.


Oh and yes I worked many years in metal and plactic fab.

Personally I have used the drill (hand and press) many times for all sorts of tapping. I have always found hand tapping to be the best. Again this is just my personal experiance