Drilling Problem

[Irish Pat]

I seem to have a problem with drilling acrylic.I do use the correct bit size,I drill on my lathe but there seem to be a bit of play in the drilled hole after I have inserted the tube.The tube seems to fit ok but when I return to the blank after drying there it is,the cap.Has something happened when the CA has hardened.
What can I do to make it fit correctly.

 

[Dan Masshardt]

Epoxy.

 

[ianjwebster]

I don't use CA for gluing the tubes in so can't help on that point - I much prefer epoxy. I did have a lot of problems drilling acrylic at first - too much heat build up. After experimenting I found what works for me. Drill a 'pilot' hole first a few sizes small than the finished size. The go back in and drill the correct size hole. Tubes fit perfectly now and no chip out of cracking. Good luck

 

[keithbyrd]

I have the same problem - sometimes. I seem to have a little bit of play in the alignment with my tail-stock and every once in a while I get the same result when lathe drilling. I turn a lot of TBC so this only shows up on longer distances. But head and tail-stock alignment might be your problem - I plan to work on mine this weekend - I really like lathe drilling but with the inconsistency I have stayed away from it. Talking about has made me guilty about not fixing it!

 

[Hendu3270]

My guess would be headstock / tailstock alignment. I've had this problem at times, but I think I've located my issue. When I put in my live center and pull up the tailstock, the centers are dead on. But I can use a center drill in my drill chuck to drill a small starter hole, switch to the size bit I need, then when I slide the tailstock back up, I can visually see the bit is slightly off center. If I drill at that point, one side of the bit will cut, and I'm left with a slightly over-sized hole. These are new bits and from what I can tell are straight. I'm blaming my cheap Harbor Freight drill chuck. Odd how it isn't consistant though. Maybe something to look into on yours if the centers are aligned properly.

 

[JTisher]

The first thing I would check is the drill bit. Even a new one can be ground wrong and if the lips are different lengths it will always drill over sized


Joe

 

[ironman123]

When I buy new bits, I get my friend, the drill doctor out and give them a fresh face and also after I have used the bit 5-6 times. Also roll them across a piece of flat glass to check straightness....paranoid I guess.

Ray

 

[plantman]

One fix for this problem after the fact I use would be this. The gap will usualy be on the end of the blank were you started to drill, the exit hole is usualy ok. When you slide your brass tube for glueing check this area to see if there is a gap betrwwe tube and blank. If there is, center your tube in the hole and add gap filling or thick CA around the space. Let it seep down inside and add more if needed. If you want to stop this before the fact, check out the alignment of all functions of your lathe. Run your headstock and tailstock together to see if they line up after being tightened down. Turn both by hand to see if you have any out of roundness in one or the other. Place a long drill bit or rod in the tailstock and turn by hand to see if there is any runout at the end. Jim S

 

[Irish Pat]

I am not sure if it is the drill bits or drill chuck because I have no problems when drilling woods or even some acrylics.

 

[Irish Pat]

Dan,why do you say Epoxy,does it expand or something over CA?

 

[randyrls]

Pat; I have often found that the drill bit specified in the instructions is not the best one. It is likely the closest commonly used size. I have a set of 115 drill bits that include fractional, letter, and number. I also have a set of metric.

I drill the hole undersize the first time, and then check the fit with the tube. When I find the correct bit to use, I write the bit size on the instruction sheet. The instruction sheet goes in my binder. There is a small difference of a few thousandths of an inch between drilling wood and drilling acrylic. The drill bit drills a slightly larger hole in Acrylic.

 

[Irish Pat]

Randy,My main problem is that one end is a good size and the other is not.I do tend to use a bit size that is suitable for the tube not whats on the sheet as you have stated.

 

[ianjwebster]

I use epoxy because it is slower setting so more time to get the tube where you want it. I tried CA and several times didn't get the tube all the way in before the glue set. More to the point of this topic epoxy is 'gap filling' and as such will 'forgive' slight errors in drilling. That way, as long as the pen band, cap, nib etc are wide enough to visually cover the gap no one will ever see / know about the minor drilling errors.

 

[plantman]

Randy,My main problem is that one end is a good size and the other is not.I do tend to use a bit size that is suitable for the tube not whats on the sheet as you have stated.

Pat; You can now buy or grind drill bits with a steeper angle on the point that will drill better holes. Use a pilot drill to start your hole, than increase the size 3 or 4 times before drilling your final size. Also having a 115 piece drill set (harbor freight) if you can get it in Ireland, which includes letter, number, and fraction bits will serve you well. Being across the pond, I would think you would have a better chance of getting metric drill bit than we do in the states. Most are made over there. Jim S

 

[gwhesser]

I was having this problem also, more prominent with acrylic than wood. Had problems getting my tailstock lined up until I bought a bore sighter and used it in my headstock with a Jacobs chuck. Once adjustments made using the bore sighter, along with drilling pilot holes, drilling slowly and lubricating with water (on acrylic), holes are MUCH more accurate.

 

[Dale Allen]

If one end of the hole is the correct size and the other is not, then it is an alignment problem.
That seems to be what you are saying, although I'm not sure.
When you are drilling the blank on the lathe, there should be no shaking or vibrating and no off-center movement of the bit.
If there is, then the hole will not be correct.

 

[ts8181]

What kind of epoxy Dan? Thanks

 

[Dan Masshardt]

What kind of epoxy Dan? Thanks

I use 5 minute 2 part epoxy. I don't think the brand matters much.

I find that it fills in very well and holds when ca might let go. I haven't really had probs with ca either. But no failures with epoxy.

Pat - you can also use gorilla glue (expanding) if you have a big gap.

However, I find that even if a tube is a bit loose in the hole, epoxy takes good care of it

 

[toddlajoie]

One thing to watch out for with Gorilla Glue (expanding, foaming polyurethane glue) is if your blanks have any cracks or voids. As the glue dries it exapands quite a bit, and generally oozes out the tube ends, but if you have voids, it will fill them from the inside out (so when you turn down, the voids you may have been able to fill with shavings and CA will now be filled with cloudy white foam..) and in the case of any cracks in the blank, it may make them worse... It does NOT have the strength to crack a blank, but it can make an existing but unnoticable crack VERY noticable. (Not that I'VE EVER had that problem...)

I've had zero glue related issues since I switched to 5 minute 2 part epoxy, and it can fill a pretty significant gap in the drilling.

 

[plantman]

One thing to watch out for with Gorilla Glue (expanding, foaming polyurethane glue) is if your blanks have any cracks or voids. As the glue dries it exapands quite a bit, and generally oozes out the tube ends, but if you have voids, it will fill them from the inside out (so when you turn down, the voids you may have been able to fill with shavings and CA will now be filled with cloudy white foam..) and in the case of any cracks in the blank, it may make them worse... It does NOT have the strength to crack a blank, but it can make an existing but unnoticable crack VERY noticable. (Not that I'VE EVER had that problem...)

I've had zero glue related issues since I switched to 5 minute 2 part epoxy, and it can fill a pretty significant gap in the drilling.

Gorilla Glue, as it expands and cures, may also shift your tube out of your blank. The way to prevent this is to put a small clamp over both ends of the blank to hold the tube inside. I personaly am not a fan of Gorilla Glue for all the reasons Todd has stated above, and I have had it open up cracks and break punky wood blanks. Besides that, it is messy and takes to long to dry. Jim S

 

[Smitty37]

CA does not have good shear strength and shear is where any forces you apply during turning and/or assembling. So in my opinion epoxy will work better.

Dan,why do you say Epoxy,does it expand or something over CA?

 

[plano_harry]

Pat, are you locking the tailstock and advancing the bit with the tail wheel? If you are sliding the tailstock forward to advance the bit, that could be your problem. On many lathes, the tailstock is not in perfect alignment until it is firmly locked to the ways. If the tailstock spindle has some side to side slop, try tightening the spindle lock slightly so that it still can be cranked forward, but doesn't wobble.