Thread: Lathe Drilling Problems

Maybe I can use Araldite in leiu of CA to take up the slack between the tube and blank until I prefect my technique.

Derek,

I drill all my blanks on the drill press with a self centering pen blank vice which works a treat. I have done some drilling on the lathe and it is quite easy with no real issue. I also use 5min Rapid Cure Epoxy adhesive which works a treat and yes all these types of glue will take up any slack and provide a great solid bond if done right.

Cheers
Tony.

I prefer epoxy to CA for most synthetics. The trick is no air-bubbles... 24hr araldite is easier to "get right" than the 5- or 15- min. stuff, even if it does mean having to wait a day or two after glue-up. .

Derek

If you are drilling on a lathe like I do then don't get too concerned. You can get a 2 jaw blank holder from McJing which will hold your blanks in place at the headstock - provided of course that your blanks are square to start with - a lot of mine are not, but it still works and so will the headstock clamp you are using.

Just put the recommended size drill into a chuck on the tail stock and away you go. Forget trying to get it exact as the tubes are never the same size as the recommended drill size. If you are lucky some will be a perfect fit, more often than not the tube will be too small for the drilled hole and thus a bit sloppy. Pen kits are unfortunately not surgical instruments so there is a great variation in what you get. Thank God the companies who make them are not also providing instruments for your doctor

You can use CA to fit the tubes into the blanks, but I don't like CA for that purpose; a lot would disagree with me. I prefer Sika poly glue, available from Bunnings at about $6 for a 250ml bottle which will last for ages. As it dries it expands and fits in the gaps between the hole you drilled and the tube. It makes a perfect fit. However, when you put the glued tube into the blank you should wrap the blank in gladwrap to cover the ends of the tube and put a small clamp over the ends as the Sika can push the tube out when drying. Be patient and give it 24 hours to dry and then away you go with turning - it leaves CA for dead. Now I wait the opinions of the CA converts

If you mean .05mm total “slop”, instead of .05mm all the way around, that’s pretty good.
Keep in mind you don’t want a snug fit between the tube and blank, there has to be a small amount of space for the glue to go, and for the brass tube to expand when we press the parts together…if it is a snug fit “dry” then when you press the pen together, the blank will crack.
Take a slimline, the hole we drill is 7.0mm, but the tube is 17/64^th (6.77mm) of an inch…same with the Sierra, a 27/64 (10.60mm) hole for a 13/32(10.32mm) dia tube, right at a 32^nd (.30mm) of an inch “slop” give or take.
Have you tried using water with a few drops of dishwashing detergent as a lube and coolant while drilling the acrylic?
The swarf can jam in the ejector grooves in a drill bit and wallow out a hole pretty quick if it gets hot.

Not to worry. I use the 24 hour araldyte to glue up my blanks. I find that it gives ages to glue up (I do batches and takes about 15 mins to glue them all so the 5min stuff is just too quick), and it also fills in any gaps in the drilled holes. I drill my blanks the same way as you describe.

Thanks guys for the advice on using Araldite and other similar products and to edblysard for the info on differences between drill and tube sizes, it's all greatly appreciated. I've saved the two blanks I was going to toss by using araldite. I'll post pics when they're done.

cheers
Derek

I don't usually loiter in this part of the forum - blame Dorno for that.

From a woodturning point of view, have you checked to make sure the headstock center and tailstock centres are in perfect alignment? If out by too much you will get a larger hole.

If you're getting a lot of slop, I'd start with a smaller bit, and work your way up. This made a big difference when I changed to this method. Now I don't do this for every blank, but I do if it's a really nice blank. And it also depends on the kit. Something with a lot of meat (like a cigar) , I don't worry about too much. But something that gets turned really thin, then it's something to consider.

EDIT: Also be sure the tale stock taper is clean. It's surprising how just a little chip can really cause problems.

I use GPW 15 min epoxy for all my glue ups (always leaving 24hrs for full cure) and use a piece of 3mm dowel to apply the epoxy to the inside of the blank and hold it up to the light to make sure the glue covers all of the inside (you can see if you missed any spots quite easily) then I apply glue to the brass tube (with dental wax plugging the end) and twist it as I push it in, that way any slop as you call it will be filled with glue. I very rarely have any failures using method even when the fit has appeared to be a bit loose. I would also check the lathe for any runout as peviously suggested just to make sure that this is not adding to the problem.