TBC bushings how to make

[Tiger]

Is there a step by step tutorial on making these? I couldn't find one but in case there is one it would really help.
My approach so far, I tried to first turn a metal workpiece between centres with both ends centre-drilled with a 60 degree angle. I haven't turned between centres on my metal lathe much I generally use the 3 jaw chuck for everything. After struggling to get the chuck off the lathe I found that there wasn't much room to cut the metal workpiece, i have a QCTP and it was just awkward, I had to extend the tailstock out a fair way but was not happy with the result. So I'm thinking the way to do it is turn the workpiece to the internal diameter of the brass tube, then put that into the Chuck and turn down for the required pen part (bushing size), then centre-drill the bushing end. Will this give me an accurate bushing or am I wasting my time?

 

[Ironwood]

Tiger if you do it that way you will almost certainly end up with out of round bushes, 3-jaw chucks are not accurate enough to do it that way.

This is how I made mine.

1- put your rod ( I used stainless rod ) in your 3-jaw with about 10mm sticking out, face off the end of the rod so its nice and flat/true.

2- loosen the chuck and bring the rod out, so there is about 60mm sticking out. You won't move it again until you have finished that bush.

3- with a nice sharp centre drill in your drill chuck, bore a centre hole in the end of the rod, use cutting fluid/coolant when drilling.

4- fit your live centre in the tailstock, and bring it into the centre hole in the end of the rod.

5- now turn the end section down to size, I normally turn about 35- 40mm long down to size to suit the pen in question.

6- leave about 15mm on the centre drilled end,now turn the part of the rod down to size that will fit inside the brass tube. It is helpful to know exactly the size you want beforehand, as you can't check the fit on the brass tube as you go here.

7- I use my parting tool to cut a nice sharp/square shoulder for the brass tube/blank to sit against.

8- once you are happy with your sizes and how it looks, use the parting tool to part off the bushing from the rest of the rod, leaving about 20mm to go inside the tube.

No doubt there are many ways to do this, but I have found this way works for me, and negates the inaccuracy of the 3-jaw chuck. ( I don't yet have a 4-jaw chuck)

 

[Tiger]

Thanks Brad, appreciate your response, here was I thinking that my method was going to do the trick. Comfortable with everything you've said except the parting tool. I have a small lathe and last time I tried to use a parting tool on it a belt broke, whether the belt was going to go anyway or whether it was my technique I'll never know.

 

[Ironwood]

You can always cut the bush off with a hacksaw, its a bit more effort but will get the job done.

That leaves the square shoulder to sort out, it you have a tool with a sharp enough point to do the job, just use that for the final cut on the shoulder and all should be good.

 

[Tiger]

Thanks again Brad, will give it a go.

 

[Donovan]

I turn all my bushes on my lathe with a 3 jaw chuck. I have .1mm run out over 500mm, so on a bush length is makes no difference at all.

Donovan

 

[Tiger]

I turn all my bushes on my lathe with a 3 jaw chuck. I have .1mm run out over 500mm, so on a bush length is makes no difference at all.

Donovan

That's pretty minimal runout, what method do you use to turn your bushings?

 

[Tiger]

Tried to make a bushing tonight but as you can't test the part that will go into the tube i made a very tight bushing. Measuring the inside diameter of the tube gave me a reading of 14.02 mm, I turned to 13.98 mm but the bushing would not slide into the tube.

 

[TBCbushings]

I use a pin guage to measure the tube and turn to that diameter to fit into the tube....I also use a CNC lathe to do all my turning.

 

[Ironwood]

Tried to make a bushing tonight but as you can't test the part that will go into the tube i made a very tight bushing. Measuring the inside diameter of the tube gave me a reading of 14.02 mm, I turned to 13.98 mm but the bushing would not slide into the tube.

Hi Tiger, when I said you need to know the size of the part that slides into the tube before you start turning the bush, I should have mentioned to turn a test piece that you can test for fit as you go, once you get a good fit on the test piece, you can measure it with you calipers and record this measurement for reference when you are turning the actual bushes.

It is hard to get a good reading with calipers measuring the inside of the brass tube, as its easy to distort the thin walls of the tube when taking the reading.

 

[Tiger]

Tried to make a bushing tonight but as you can't test the part that will go into the tube i made a very tight bushing. Measuring the inside diameter of the tube gave me a reading of 14.02 mm, I turned to 13.98 mm but the bushing would not slide into the tube.

Hi Tiger, when I said you need to know the size of the part that slides into the tube before you start turning the bush, I should have mentioned to turn a test piece that you can test for fit as you go, once you get a good fit on the test piece, you can measure it with you calipers and record this measurement for reference when you are turning the actual bushes.

It is hard to get a good reading with calipers measuring the inside of the brass tube, as its easy to distort the thin walls of the tube when taking the reading.

I'm assuming there's no way to rescue the bushing I've made, by the way as the TBC bushings are supposed to slip inside the tube when you're turning, how do you accurately measure run-out on these types of bushings so that you know ther're ok.

 

[Ironwood]

Put the bush in your 3-jaw chuck and see how much runout there is , the 2 diameters on the bush should be perfectly concentric, so any runout will be due to the inaccuracy of the chuck. Do you have a dial indicator ? You can get a bit of a feel by holding your thumbnail on the bush while its spinning slowly.
If it just requires a little bit to get a nice fit, you could try sanding the high spots off with some 120 w&d, I have also used a flat file to do this, be careful with the file and the chuck jaws though, you dont want to wear the file.

Once you get both bushes made, test your set-up by putting a brass tube between the bushes and spin it between centres on your lathe, if you have a dial indicator use that.
If everything is good, you should have no runout at all on either of the bushes or the brass tube.

 

[Tiger]

Thanks Brad, I have a dial indicator and will test this, everything looks fine with the bushing except that it won't fit into the tube. With all the kits that I use, I'm going to need at least 28 bushings, at the rate I work, I'll be doing this for the next few weeks!

 

[Ironwood]

Yeah takes me a while to make them as well.
I stopped after making 4 or 5 sets, I made a set each for my main sellers, everything else I just turn between centres, no bushes.
Even when I do start with my bushes, once I get down to within about 1mm of finished size I ditch the bushes and take the last few cuts, sand, and finish without the bushes.

 

[Donovan]

I turn all my bushes on my lathe with a 3 jaw chuck. I have .1mm run out over 500mm, so on a bush length is makes no difference at all.

Donovan

That's pretty minimal runout, what method do you use to turn your bushings?

I turn my bushes out of silversteel. I finish the bush without removing it from the lathe. Once I part it of I turn it around and put a chamfer on the part that goes in to the tube. They normally fit LOL