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Drilling on a mini-lathe
Lathes are extremely good at drilling holes in the middle of things. I have a 13mm chuck installed in the tailstock of my lathe. This holds a drill bit steady whilst the lathe spins the job. The basic principle is that you turn the handle on the end of the tailstock to move the drill into the job and cut a hole. All being well, it makes a nice hole in the middle.
Drilling may be done to make a particular sized hole in a job, or, it may be used to simply make a big hole in the end as the initial stage of a boring operation. Boring allows you to make a much bigger hole.
The main problem with drilling a hole with a lathe is the fact that all drill bits bend. If you put a drill bit in the chuck and try to drill a hole down the centre of the job, chances are it will not end up in the centre.. you have to be a tiny bit clever. This might not concern you if you are just drilling a hole that you are going to bore out, but I have discovered that its an important aspect.
These are the steps I take to drill a hole in a job with my mini-lathe.
- Let us first look at the operations on the tailstock. A tool can be inserted into the hole on the chuck side, and is held in my virtue of the Morse Taper on the tool. The tool can be a dead centre, a live centre or a chuck. Probably other things too, but I haven't learn about them yet.
- Winding the handle on the back moves the tool in and out. There is just over 1 inch of travel.
- The tailstock can be bolted down tightly to the beds.
- THe black handle on the top is used to lock the tool in the tailstock.
- So, I insert the chuck into the tailstock and tighten the handle so that I can only just move the position handle.
- Then you need a special short bit called a centre drill. This bit won't flex like a normal bit. I don't have a one of these, so I use a short bit normally intended for countersinking to make a small pilot hole in the job before using the main drill bit.
- Once the bit is tight in the chuck and the toolpost/carriage safely out of the way, spin up the lathe to a slow/medium speed.
- Wind the tail stock so the drill bit is as far from the chuck as it goes without pushing the taper out.
- Loosen the bolt that secures the tail stock to the lathe, and move the tail stock so that the tip of the drill bit is very close to the job.
- Now tighten up the nut that holds the tail stock to the beds.
- The tip should be lined up with the centre of the job.. if not, adjust the toolpost.
- Apply lots of cutting fluid and slowly move the drill into the job, making the small pilot in the end of the job. As you turn the handle on the back of the tail stock, it should move the drill bit into the job... if you have not got the tail stock tight, it might move the tailstock backwards. If the job is not held securely, it might push the job deeper into the jaws of the lathe chuck.
- Once you have a small hole, back out the drill, unbolt the tail stock, move it back, and change to a normal drill bit.
- Move the tailstock back up so the drill nearly touches the job and lock down the tailstock bolt again.
- The turn the handle on the back to drill into the job.
- Only go about 1/4 inch before coming out, cleaning off the swarf and applying more fluid.
- To drill a very deep hole, you will have to keep stopping and moving the tail stock further and further in.
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