Here is a list of all the postings Martin Kyte has made in our forums. Click on a thread name to jump to the thread.
|Thread: stepper driver|
Excitation is microspepping as you say. Stop current would be standby or holding current when not stepping. Set as low as you like to provide enough of a 'detent'. It's a worm drive so it's unlikely to move anyhow.
Don't know about the decay setting. I'd set it to 25% and see how you go. (tune for minimum buzz and check you are not losing any steps. What's the part number?
|Thread: Precision division plates|
Nice one Mike.
Fair comment Adrian regarding gear, shows I wasn't really thinking about that bit.
But back to your sun. The edge is not sharply defined. The telescope you use will have a limit to it's resolution. You have atmospheric distortion to consider. The rotaion of the earth is not constant. You have stabilty effects. The angular size of the sun is about 0.5 degrees so you need to fix the edge or the centre to better than 0.05 % of the disc to get an accuracy of 1 arc sec (if my maths is right) and the distortion in the atmosphere is going to be worse than that when the sun's out . Far better off using a big disc with graduations round the edge or ball bearings as has been suggested.
At least with the mirror and the wall you can put the wall as far away as you like to get the accuracy you want.
OK I'll bite
1. The sun is not a point object so you have to assess the centre of the disc.
2. You are still essentially measuring angles when you really want to measure distance of arc.
Ditch the sun and use a star
Ditch the astronomy and reduce to movements you can measure directly such as.
Fit a mirror to the centre of the plate and bounce a laser beam off it so that the beam is projected onto a distant wall. Make a mark.
Measure the distance to the wall from the mirror. Calculate how far you need the spot to move to give you your required angle. Make a second mark on the wall at that distanceTurn the plate so that the spot falls on the new mark. Drill your hole or cut your tooth. adjust the mirror so that the spot falls on the first mark again and repeat.
Or you may like to think that you could make a second worm wheel from your supposedly inaccurate head which by the logic of your first paragraph is going to be 40 times as good as the old one.
|Thread: Lathe screwcutting|
Are you using any cutting oil?
|Thread: Just Done Something Stupid!!|
Purely as an academic question as you have settled on a solution.
What would people think about fitting an additional access bush in the crown. One could drill the required holes in the original steam pipe through the hole and then fit a bush and blanking plug. I don't know how bothered boiler inspectors get about additional bushes. Not very I suspect and of course there needs to be space in which to fit the said bush.
|Thread: Silver soldering a blind 'mortise and tenon' joint.|
I wouldn't bother with the thread just a cylindrical loctite joint.
|Thread: Machining cork!|
Razer blada mounted vertically. Feed slowly and run the lathe fast. Essentially you take small slices from the face of the cork to full depth required. Either Geo Thomas or more probably Tubal Cain described this eons ago. Works on rubber too.
|Thread: Myford S7 countershaft bush temperature|
I suspect that the 'factory' just pressed the bushes in and left it at that.
|Thread: Window deflection query|
We have a 'glass wall' of 2m hight architectural glass panels around our rooftop restaraunt at work which are cantelever supported at the bottom edge. They move a good 2-3 inches at the top in a strong wind. I suspect most of the 'worry' is because we intuitlively think of glass as rigid.
|Thread: Can opener - the holy grail in engineering?|
You need a Bonzer. They are indestructable. Trouble is you really need a farmhouse table to mount it on.
Edited By Martin Kyte on 04/03/2019 09:45:04
|Thread: Myford S7 countershaft bush temperature|
You could slacken off the spindle drive belt a little. Those link belts are a bit stretchy to my mind and can be deceptive as to tension. They grip quite well so they don't need to be any tighter than needs be. So long as then are not slipping under normal conditions it's no bad thing to have the belt slip when something goes wrong.
|Thread: New Bush - steel, brass or...?|
Generally best to use dissimilar metals. I'd go for brass. Lubrication would be a step forwards though.
Well if it's Heath Robinson, Lignum Vitae would be more in keeping. Seriously what usually happens is hard particles embed in the softer material which then wears the harder surface. Old clocks do it. Dust particles embed in the brass clock wheels and erode the hardened steel pinions. How long did it take to wear out with the original configuration. If it's 10 years or so you may as well just do the same as last time.
|Thread: Myford cross slide backlash|
Adjusting the collar will take the backlash out of the cross-slide bracket/leadscrew interface with the proviso that as it needs to turn freely it will need some clearance. It can do nothing for the backlash between the leadscrew nut and the leadscrew.
|Thread: 3 Jaw self centering ER chuck|
I think if you have a cnc machine with an air operated 3 jaw chuck then with the addition of 3 special jaws you have an adaptor to take the full range of ER collets and can safely hold thin walled tube. Not a bad result for not much outlay.
Are the jaws air operated ?
Looks like it would be optimum for a fixed diameter only.
|Thread: which mill|
Streach to the VMC even if you have to wait a little before upgrading to DRO.
|Thread: Tube Seam|
Certainly is. In USB comunications it is used in the sense of an abstract entity describing a data flow and is defined in terms of it's endpoints when configured An unconfigured endpoint is called an endpoint while a configured endpoint is called a pipe. Which fits nicely with my preferrence of pipe as a functional term.
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