Drilling acrylic blanks for pen tubes

[PolishPenTurner]

Hello,
I've turned a number of pens recently and just started turning acryclic pen blanks. I seem to be having issues in the couple of acryclic pen blanks I've drilled. The first one I drilled out ended up cracking the blank on the outbound side of the pen blank (I didn't have a backer board supporting it when the drill exited the pen blank...dummy me!). The 2nd acrylic pen blank I drilled was successful....but tonight I tried drilling another acrylic pen blank (the first half of a 2 barrel pen kit) and, as I did with the others, I pretty much let the drill bit do most of the work and I cleared out the shavings every 1/4" or so. However, when I punched through the end of the pen blank the drill bit grabbed the acrylic with force twisting my wrist (I was using the Rockler drill guide and vice) and the drill bit locked into the acrylic blank and I can't get it out. I even put the drill bit and pen blank into my bench top drill press along with the pen blank vice (Rockler) and when I had things locked in place I turned the drill on and it wouldn't budge...the drill press couldn't even remove the drill bit.

Has anybody experienced this while drilling acrylic pen blanks? Should I be using a different type of drill bit for acrylic blanks? I haven't had a lot of luck drilling the few acrylic pen blanks I've tried so just wondering if I'm doing something wrong. I really want to use more acrylic pen blanks because they are all so unique and beautiful....but unless I get this figured out I may change my tune.

I'm going to attempt to attach a picture of the drill bit stuck in the pen blank...but I've never attempted to attach a jpeg in this forum...so hopefully it comes through ok.

Thanks for any advice you can provide.

Jeff

 

[ValleyBoy]

Hi Jeff

I remember this happening to me once when I first started. So you’re not alone.
It’s basically because the drill got too hot. The blank has briefly melted enough to fuse itself to the drill and you won’t get it out without destroying the blank.
I believe the rockler jig uses a hand drill and I would suggest you move away from drilling the blanks like this as it’s very hard to control the revs. It doesn’t matter so much with wood but plastics are a different beast.

I always drill on the lathe and control the rpms as well as the rate I feed the drill so as to avoid this. It doesn’t take much to overheat so you do have to be careful and start with low revs. You still need to drill a little at a time as you’ve been doing. If you feel the drill each time you withdraw it, (be careful as it gets very hot), it’ll give you an idea of how far you can push it. If you see smoke then you’re going too far/too fast.
Hope that helps.
Cheers
Ash

 

[clement1]

when I have to drill acrylic blanks I always do it at low speed and I cool it with a little water, you also have to regularly lift the bit to evacuate the shavings.
I thus avoid the cracking of the blanks.
Hope this helps

 

[MikeC]

You could try drilling on the lathe as Ash suggests.
Also consider starting each hole with a centring bit, and then creep up to the desired diameter in stages using smaller drill bits.
That means that by the time you get to the correct diameter drill bit, there isn't much for it to remove and heat isn't so much of a problem.
Mike

 

[flexi]

Just to add my bit, I always leave a waste section on the blank 5-6mm this is sacrificial and if any chip out occur it's normally within this bit which is cut off...

 

[PolishPenTurner]

All of this is great information folks. I greatly appreciate the input. I hadn't thought of using the lathe to drill....or testing the heat on the bit. This all makes sense now that you folks have pointed this out....since acrylics are plastic. Now I have to figure out how to get the blank removed from my drill bit. I'll probably just end up throwing it out at this point. And I'll have to check my lathe chuck to see if I can crank it down low enough to accept a 3/4" square pen blank.

I was doing some research last night and Penn State Industries has a 7mm drill bit that they say is made for drilling acrylics.

7mm Acrylic Blank Drill Bit

Are you tired and frustrated of splitting and tearing your plastic pen blanks when you drill? Now your problems are solved! With this new, dedicated High Speed Steel Acrylic Blank Drill Bit you'll be amazed how quickly and precisely you'll drill through your Acrylic pen blanks. So you ca

www.pennstateind.com

...however based on what you guys have mentioned I tend to believe the heat factor is my issue and this type of drill bit is more marketing than anything.

I appreciate all your inputs I've got a couple more acrylic blanks to drill today so I'll try and post an update on my hopeful success when I try these methods.

 

[PolishPenTurner]

Hey folks....I've been doing more research on drilling acrylic pen blanks. PSI has a drill bit set that is specifically designed for acrylic pen blanks. They say those drill bits run cooler but they appear to be a bit more expensive as well.

From your experiences regarding acrylic pen blanks...is this worthy of looking into? I'm going to reach out to PSI on Monday to ask this same question...as well as....can these acrylic bits be used to cut wood as well? Logically I would say if they are made to run cooler for acrylic bits...then they should also be able to be used on wood pen blanks.

I may be overthinking this....but wanted to check with all of you to see if you have any suggestions/thoughts?

Thanks,
Jeff

 

[alpha1]

I think your problem is heat. I dont think you need a special drill. Drill slower and peck drill. Ideally drill on the lathe.

 

[ValleyBoy]

If you are going to drill on the lathe then get yourself a set of centre drill bits. They are inexpensive but are a essential really. No matter how well your lathe is aligned a drill will often tend to wander a little as you initially introduce it to the work piece. Starting off with a centre drill really does help line the drill up onto the correct path. The centre bit creates a conical shaped hole (always use one that is smaller than the drill) and then when you start drilling go slow until you see the tip of the drill drift into this pre-made hole.
A bit of lubrication helps too. I use mineral oil but water (some use soapy water) or other oils work too.
As for drill bits I don’t think it matters too much but I get mine from Beaufort ink (who do a variety of drills for most standard pen kit sizes) or ukdrills.com who do every size imaginable.
Cheers
Ash

 

[Hallelujahal]

Just my 2p but drilling on the lathe using pen jaws in the chuck was a game changer for me!

 

[PolishPenTurner]

Thanks again for the great input guys. Going out to the shop now to try some of these methods. I'll let you know how everything turns out.

 

[PolishPenTurner]

Alex....question.....what kind of pen jaws do you use in your chuck? I have an EasyWood Tools Easy Chuck but I'm not sure they make small jaws for pen blanks. I have seen some jaws that are standalone for pen blanks but was curious as to what you're using.

 

[MikeC]

Don't fully give up on that blank yet.
Pour boiling water over the blank with the drill bit in it, and hopefully the different materials of plastic and metal will expand and then contract at different rates and with a bit of persuasion the drill will move enough to free it.
I did this once by putting the drill bit into the chuck and by holding the spindle at the headstock end (obviously but to reinforce with the lathe switched off) -to give extra purchase, was able to free the drill by using mole grips on the blank.
Also, on close inspection of your photo, although it isn't fully clear, the drill flute seems to have entered the blank, and if it has that may have contributed your original problem.
Mike

 

[Dario]

As a general recommendation, prior to going down the road of buying individual drill bits, I suggest buying a quality drill bit set*. It'll save money in the long run especially if you plan on using a variety of different kits.

As a personal recommendation, I've found that when I invested in really quality drill blow outs, heat and a number of other issues just kind of disappeared. I like the CLE-Line 135° split point/high speed steel sets. They just tend to run cooler for longer - though I still have to back the drill bit out regularly for material removal.

* or rather two: one metric, one SAE

 

[Dario]

Alex....question.....what kind of pen jaws do you use in your chuck? I have an EasyWood Tools Easy Chuck but I'm not sure they make small jaws for pen blanks. I have seen some jaws that are standalone for pen blanks but was curious as to what you're using.

Not Alex but I use the following for drilling on my lathe
Pen Jaws for my Nova chuck (other jaws exist for other chucks) : https://www.amazon.com/NOVA-6034-Pen-Plus-Jaws/dp/B00EUUMZG8
Drill chuck - https://www.pennstateind.com/store/TM32KL.html

Those jaws do have a limitation of not being able to take blanks wider than 1.3"/3cm.. ish. I haven't worked out the exact numbers.

Here's one that can handle larger sizes - https://www.pennstateind.com/store/CSCPENCHK2.html.

Here's an article I just ran across - https://www.woodworkersjournal.com/a-primer-for-drilling-on-the-lathe/

 

[Dario]

Doing a bit of research (because it's weed pulling day) this might work for your chuck

1/2" Easy Reach Dovetail Jaws | Easy Wood Tools

The CJ210 Jaws are optional equipment for our Easy Chuck. The dovetail jaws grip tenons at 1/2"+ and expand in mortises at 1-1/4"+, jaw length is 1-1/4". The CJ210 Jaws work only with the genuine Easy Chuck. Easy Chuck not included.

www.easywoodtools.com

It's not much cheaper than the PSI item listed above.
Though in honesty I personally have a /potential/ concern with the PSI.
It does have the advantages of a) being able handle larger items and b) a dedicated chuck cuts down on the number of times you have to swap face plates out. However as a bit of a klutz who often has to learn things the hard way, I'm not too keen on it only holding the blanks by 2 corners.

 

[Hallelujahal]

Alex....question.....what kind of pen jaws do you use in your chuck? I have an EasyWood Tools Easy Chuck but I'm not sure they make small jaws for pen blanks. I have seen some jaws that are standalone for pen blanks but was curious as to what you're using.

Hi sorry I’m so late in replying. I have the Nova G3 chuck and purchased the pen jaws.
Jaws: https://www.poolewood.co.uk/product/nova-6034-pen-plus-jaws/?v=79cba1185463

Chuck: https://www.yandles.co.uk/nova-pro-tek-g3-scroll-chuck-direct-thread-m33-x-35mm-48292/p26941

Hope this helps!

 

[alpha1]

I bought a set of soft jaws for my four jaw chuck on the metal lathe. I have marked them up to accept the pen jaws i just need to drill and tap them then they can be fitted to my metal lathe.

 

[alpha1]

Update I have been messing with the diferent sets of chuck jaws to see what the difference is. I have come to the conclusion that if I pop the Axminster lathe jaws on my Milling machine I can modify them to fit on my metal lathe this then gives me the option to use any of the Chuck fittings on the metal lathe. An interesting project that will keep me out of michief for the week end. But un likely I will use anything other than the pen jaws on the meatal lathe. Of course if it works and some one else has a metal lathe they would like to mount pen jaws on ???

 

[PolishPenTurner]

Quick update folks on my frozen drill bit in the acrylic pen blank. I tried a number of things based on your inputs. I first tried heating up the pen blank with a torch and turning the blank...FAILED. Next I tried putting it in the oven for 20-25 minutes at 170 degrees (lowest our oven will go)...FAILED. What I finally decided to do was to boil some water and I dipped the bit and pen blank in the boiling water for 2-3 minutes....and voila...SUCCESS.

This was a learning process for me...what NOT to do so hopefully it won't happen again. But then again...I'm Polish...so it's possible! :)...but at least I know what to do to free up the bit this time.

I also ordered that large dedicated pen blank drilling chuck from PSI yesterday so hoping that makes drilling pen blanks much easier!

Thanks to all of you for your great ideas.