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Member postings for C J

Here is a list of all the postings C J has made in our forums. Click on a thread name to jump to the thread.

Thread: Stroboscopic effect
29/06/2020 23:00:28

To return to my original post, I successfully cut the custom recess in the soft jaws without any lighting jiggery pokery, after I remembered my lathe has a DRO!? and once I had the diameter set I didn't need to look at the chuck after all blush


And my final take on the effect is it might have also been alleviated if I had stuck a card mask on the jaws, so similar to the masking off used in an operating theatre, I could only see and focus on the area I was working on?


Edited By C J on 29/06/2020 23:03:51

Thread: The fit of tapers
28/06/2020 15:20:06

Curve ball accepted but not to mention the dreaded galling that can also occur

And to misquote a Monty Python sketch “No one expects the dreaded galling”

Edited By C J on 28/06/2020 15:23:09

28/06/2020 15:04:53

That's right, but for added fun my disc is driven by six lobes as shown.


Thread: Stroboscopic effect
28/06/2020 14:32:21

In an experiment, I was able to still a line of Tippex drawn on the chuck using a strobe app on my IPhone but the illumination was dependant on the angle and insufficient to overcome the spinning jaws which also reflected the light.

So while I won't pursue this idea, I found it interesting.

Edited By C J on 28/06/2020 14:38:20

Edited By C J on 28/06/2020 14:40:08

Edited By C J on 28/06/2020 14:42:33

28/06/2020 13:12:30

I'm using a boring bar to slowly cut a custom recess into some soft jaws mounted in the three jaw chuck of my S7 and I'm gauging the end of the cut, the final diameter, by eye, but the three jaws are producing a strong stroboscopic effect at the chosen spindle speed.

So my question is has anyone considered the use of a stroboscopic lamp geared to the spindle to counteract this effect and make the workpiece appear stationary?

Thread: The fit of tapers
28/06/2020 11:42:43

Love that idea but I’m locked into using a ready made disc, and I once had a go on a Manx Norton albeit round a field!

28/06/2020 11:20:15

I am constantly surprised by the depth of knowledge to be found on this forum.

28/06/2020 11:10:40

Thank you Martin,

That gives me an idea of the linear movement that could occur.

As it will only be driving a small carbon fibre disc I don’t expect the hub to experience any serious torque, or slip, but most likely I will remove and refit it a few times to adjust the inlet port timing.

28/06/2020 07:04:26

Interesting, but I think I will have to suck it and see, as the taper on my shaft must then be a locking taper as if was made to take a mag/flywheel.

And I claim that this problem found me instead of the other way round

28/06/2020 06:34:12

Yes all of those things, but I was hoping someone might come up with a formula that states, if all these conditions are met, then, say the the linear tolerance for an MT2 taper is this etc.

28/06/2020 05:52:34

I am going to make a flanged hub to drive a disc valve for my motorbike, the flange will have about 1.5mm clearance on either side of the housing in which it is to fit.

The problem I face is that this hub must fit on a tapered shaft, and whilst I can machine the hub to fit so that it’s flange has an equal clearance in the housing, by repeatedly fitting the hub on the shaft, it made me think “well how repeatable is the linear fit of a taper joint” and how much creep occurs before they lock? and similar questions.

Broadly speaking, I guess that tapers with steeper angles lock with a tighter linear tolerance than tapers with shallow angles.





Edited By C J on 28/06/2020 05:53:59

Thread: A round peg in a round hole
13/06/2020 19:16:02

Oh well sad back to the drawing board, or lathe.



Edited By C J on 13/06/2020 19:18:37

13/06/2020 18:49:23

But of a disappointment, as I found the central cutter hole of my boring head doesn’t spin true by 0.5 mm at right angles to it’s slide, so as things stand I can’t start from true, or on this hole anyway!




Edited By C J on 13/06/2020 19:02:33

13/06/2020 09:39:42

Sorry, Yes I do have one, and thought of cutting the pegs mounted on a vertical slide with the cutting tool in the other way round, but now I’m sold on the idea of a peg holder fitted in my MT2 boring bar head held by a draw bar in spindle of my S7

Not a great deal of mass flying round and simple

Edited By C J on 13/06/2020 09:40:36

13/06/2020 08:55:20

.... in which the workpiece is held by grub screws and I could dial in as much or less 180 degree eccentricity as I like

Sounds like job done!

13/06/2020 08:45:32

Jason, Are you suggesting I make a peg holder to fit into a boring head?

Edited By C J on 13/06/2020 08:47:36

13/06/2020 08:38:37

I see what you mean but I am trying to avoid tedium and like the idea of a dial-able cross slide Set up

13/06/2020 08:12:26

I want to make a number of round pegs with a central flange to join some round tubes with brazing but I want the diameter on one side of the flange to be eccentric to the other by varying amounts on each peg.

I have seen the trick where a piece of metal is placed between the jaw of a chuck and the workpiece to create eccentricity but I would like to be able to dial it in like you can with some boring bar heads.

The tubes to be joined have an inside diameter of 15mm so I have thought of using a small chuck mounted on a small dovetail cross slide, which in turn is mounted on a faceplate, which might seem like overkill and something only to be used at low speed but one that would produce repeatable results, if I can first find a lightweight, low profile cross slide for this set up?





Edited By C J on 13/06/2020 08:14:47

Thread: 3D CAD software - what do you use?
19/05/2020 18:40:17

I still mourn the loss of Google Sketchup which was very user friendly

Thread: Turning oil filled bushes!
19/05/2020 15:52:01

Thank you, that must be The definitive answer

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