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Member postings for John Haine

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

Thread: small toothed belts
19/08/2021 10:25:05

RS and Farnell/CPC

Thread: Harrison Remontoire info
19/08/2021 09:37:22

**LINK**

Thread: Dore Westbury x slide motorising
18/08/2021 16:09:26

img_20200718_174914405_hdr.jpg

My VMB has a handle at each end. The LH one is modified to take a timing belt pulley and a pin clutch. Feeding manually I use the RH handle but I could use the LH one. It has lost it's micrometer scale but I have a DRO anyway. I'm sure a micrometer scale could be retained I just didn't need it. Sureley you do something like this at whatever end has the feed handle?

Thread: going carbide on a Myford
18/08/2021 09:33:26

I have a Super 7 and all the tools in QC toolholders are carbide except for one tangential tool and a home-ground 60* threading tool. No problems. An existence proof that carbide works fine in a Myford.

Thread: Design Award
18/08/2021 09:30:50

Good idea in principle, but very frequently when using steps there isn't a handy vertical surface to prop this against - for example reaching a high shelf in a floor to ceiling cupboard.

Thread: Taper reaming
17/08/2021 11:51:55

Ah well, shoorting video is free, you had to pay for film!

Thread: Converting fractions to decimals
17/08/2021 11:47:55

I'm bemused by all this. I haven't used fractions really since I did basic arithmetic, whether I'm using inch or metric measurement. If I need to convert I do it in my head or use the calculator on my phone. This has a basic one provided but I usually use a freeware app called Free42 that emulates an HP42.

Thread: Tinkering with Gary Liming's Stepper Motor control sketch
16/08/2021 11:33:54

Looking slightly more closely and making a wild guess, I think that originally Gary assumed that there would be a simple reduction gear ratio like 1/4, but then people were saying that their mechanics had ratios like 3/4 - so the parameter "3" would be the numerator (top) and "front end gearing" would be set to 4.

16/08/2021 11:28:50

Without looking in more detail at the Gary Liming site I can't think what GearRatio1top can be but I suggest that you set it to 1, as also the "front end gearing".

16/08/2021 11:25:12

A simple thing to do is change the microstep setting from 8 to 2 or 4. You get 200 steps per rev from the "native" stepper motor and the microstepping function in the driver interpolates 8 additional steps in between so the motor will take 1600 steps for one rev, I'm not familiar with the software you mention but I would guess that "front end gearing" refers to any mechanical reduction between the motor shaft and what it's driving. If for example there was a 2:1 reduction this would increase the effective steps per rev to 3200.

Edited By John Haine on 16/08/2021 11:26:47

Thread: Dividing this would have been an interesting exercise !!
16/08/2021 10:33:44

Thanks Martin. The Wiki article also mentions that it can be used for lens testing. The device seems to meet the requirements for a Ronchi test grating pretty well.

16/08/2021 09:27:10

Maybe like this:

**LINK**

16/08/2021 09:20:01

I am pretty certain that this is not a spectrograph grating. There are too few wires, which would give a very dim image; and the spacing is too large for optical wavelengths which would make the first order spectrum very close to boresight. As Martin and another previous poster have suggested this is most likely to be an aid to mirror or lens testing - Martin maybe you could describe how the gratings you made were used?

15/08/2021 12:33:36

Different Oak Ridge - this one is in Massachusetts, the "nuclear" one in Tennessee.

Thread: choices of material to turn
15/08/2021 10:35:11

Looking that steel up it is leaded free cutting so should be pretty good. Don't even think about stainless until you have some experience with ordinary steel, but when you do, 316 is a reasonably machinable grade.

Thread: Dividing this would have been an interesting exercise !!
15/08/2021 10:31:58
Posted by Michael Gilligan on 15/08/2021 10:20:22:
Posted by Dave S on 15/08/2021 10:01:22:

[…]

Edited to add: the circular pin layout is purely aesthetic, […]

.
… and that’s what piqued my interest : The craftsmanship that appears to have gone into that elegant but unnecessary layout.

MichaelG.

Well no, surely? If the rows were straight either the aperture would have to be smaller or the OD larger which might not fit. If it was microwave it wouldn't be used on an optical telescope, and the spacing is too large even for infra red.

I think Bernard is on the right lines, it generates a diffraction pattern in the telescope focal plane when focused on a bright star, which is characteristic of the optical performance. Ideally if the spatial frequency of the wires is constant across the array there should just be a single line, but that would be smeared out by aberrations. Maybe Neil could cast some (coherent) light as our resident astronomer?

15/08/2021 09:34:21

Never mind how they made it, with a spacing of ~1/16" what was it used for?

Thread: Broken keyless chuck
12/08/2021 20:41:59

I am fairly certain that this has been answered previously on this forum. Use the Google search facility on the homepage. Or maybe Michael Gilligan will chime in as his search skills are excellent.

Thread: Hoover AC Motor and Dewhurst forward/reverse switch wiring
12/08/2021 16:47:24

Um, can't see any photos?

Thread: What Type/Gauge wire is best for soldering onto Arduino shields
08/08/2021 16:34:34

I try to avoid soldering connecting wires since they are hard to get off! Preferred method is either to solder in a header pin and use an appropriate female connector on the (stranded) wire; or solder in a small screw terminal block. You can get sets of connecting wires with ready applied female connectors at each end quite cheaply, and in lengths where if necessary you cut it in the middle to get two or cut the connector off one end. The screw terminal blocks are available from the likes of RS or Farnell. Header pins available from many suppliers, like the ones used on Arduino boards in strips. Just snip off the number you need. You can also get kits to crimp a female header connector on the end of a bit of wire but I've never mastered that. Use stranded wire, ~1mm dia or a bit bigger.

**LINK**

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