Drilling on the Lathe

[rickstef]

To those who drill their blanks on the lathe, I have a couple of questions, and I am hoping for answers that will shed light on the problems I have been seeing as I drill on the lathe.

First, what RPM or RPM range do you drill at?
Second, do you use a long or a short drill bit?
Third, when gluing the tubes into the blank, have you seen a space/void where the blank fails to glue to the entire drill hole?
Fourth, if you did experience what I describe in #3, what do you do?
Fifth, would the gap problem be solved by using an expanding type if glue(Gorilla/Sumo)?

I have been drilling my blanks on my lathe, around 1100 rpm, and I get a pronounced widening of the blank on the end that gets drilled first, the end is usually perfectly round, it is frustrating to see this.

Is there trick I am missing?

Rick

 

[Richard Gibson]

Just a guess that your bit may be bent. I drill on the lathe at about 800 rpm and use regular length bits. Not really had any problems with to big of hole. I glue in with epoxy and put it on fairly thick so if there is any gap, it fills it.

 

[rsetina]

I've drilled a couple of wood blanks and haven't had any trouble with a oblong or oversized hole on the end. I try to make sure the blank is centered on the drill bit and to help the bit center itself I use an awl to poke a small hole in the end before drilling. Both blanks wobbled slightly as the bit touched the wood but centered right away.

 

[rickstef]

I am using a Colt 7mm for most of my drilling, and I know the bit is true

 

[watch_art]

From all the reading I've done - when drilling either on the lathe or a DP, doesn't matter - if you don't pull the bit out frequently, say every 1/2 inch of drilling, the waste can actually cut your hole bigger and give you a wonky hole (if you're drilling plastics - don't know how wood will react...). So you have to constantly pull the bit out and clear the waste. I also use a bit of cooking oil on the bit. I was using PAM but the smell made me ill.

I have my lathe set to the highest speed pulleys, with the lowest speed being about 1300, and that's where I drill. It's a Delta 46 460.
If just the end of the hole is wider, it could be that the head and tail are out of line just a little bit.

 

[okiebugg]

small hole

I find that if I have this problem, The next blank I drill will have a small pilot hole drilled in the blank before putting your regular bit into contact with the blank. Your drill bit will follow the smaller hole and has less chance to drift....Thus called a 'follow hole' That's Just FWIW

 

[flyitfast]

I had a similar problem with a larger hole on the acrylic blanks. I think the drill was wandering at the start. I started using starter bits to make a guide hole and the problem went away. Starter bits are short bits and much stiffer and the bit a chance to stabilize. I got them from HF and they were about $5 for five different sizes. They will last forever.
Works for me when drilling on the lathe.
gordon

 

[KBs Pensnmore]

'follow hole' ???????

I find that if I have this problem, The next blank I drill will have a small pilot hole drilled in the blank before putting your regular bit into contact with the blank. Your drill bit will follow the smaller hole and has less chance to drift....Thus called a 'follow hole' That's Just FWIW

Okiebugg, I think you will find it is called a pilot hole.
Kryn

 

[ROBCTRY69]

had the same problem with a new bit from psi got to chacking and the bit was bent im using a shorter bit i had from harbor frieght and having no problems was drilling on slow switched to high speed last night and believe it worked better not sure till i drill a few more

 

[glycerine]

Check your headstock/tailstock alignment. I've had this happen to a small degree because my tailstock was slightly to the left or right of center. When the drill bit goes in, it's off center and makes a wider hole, but corrects itself the rest of the way through...

 

[Ted iin Michigan]

Good advice above. I've just started drilling on the lathe and have experienced what you describe. Several things to focus on: 1 - Sharp bit. 2 - Suggest you try slowing down the lathe speed if you can. 3 - Make sure the headstock/tailstock alignment is dead on. 4 - Really important - make sure you are hitting dead center on the blank when you start drilling.

Good luck

 

[moke]

Rick,
I have personally never had a blank that the hole was oversize on one end, but I have heard of a guy that did...lol....

Actually I have had that happen more than a few times. IMHO these are things that can contirute to curing the problem.
1. the mentioned alignment of your tail/headstock
2. the mentioned bent drill----roll the drill bit on your TS to see if it is round
3. Absolutely as mentioned, use a starter drill, I think that is huge! They are cheap. HF even has them
4. Use a normal length bit and hold the chuck with your left hand while drilling
5. use a good chuck to hold the blank, a dedicated drill chuck from PSI or collet chuck after the blank is round--something repeatable and with no slop...I personally have had issue with 4 jaw chucks and getting the blank perfectly centered.
6. Rpms 500 to 800...go slow, I blow air into the hole to cool it and the bit...clean out as mentioned frequently
7. I cut my blanks a little long and do not drill all the way, then trim later. This requires some thought if you are going to match a pattern...I always drill the ends that need to match.
8. After drilling I have been LIGHTLY filing with a rat tail file, but be very careful to not make the end bigger by dragging it. (I also like how Dr Strangefart has been using a gun bore cleaning brush, but have not done it yet) I think that should be done on a DP or cordless drill.
9. I have used gorilla glue with good success for the above mentioned problem. I have also used epoxy and CA then added some extra with a toothpick into the gap and forced it in with air. Be sure to plug you tube before you do that. Penman1 suggests using plumbers putty which is awesome and cheap too.....

Again this is just my .02.