Member postings for Martin Connelly

If this motor has a start capacitor you would expect it to disconnect once the motor is up to speed. If the centrifugal switch that disconnects it only works correctly in one direction then you will have the start windings powered up all the time when running reversed and the motor will overheat. Also some motors have offset brushes and should not be run in reverse. This may be an example of this.

Martin

Looks like heat conducting paste that has dried out. Does the switch have any electronics in it?

Martin

Select the lines that are the boundaries that you will be cutting to and enter or click the mouse button set up as enter. Then select the piece of each line that you want to remove. Note that if the lines are not all on a single plane you may have problems. This is not a problem if you are using a 2d version.

Martin

Ps sometimes the screen may need refreshing to show the result. Zoom in and out is one way to refresh the screen. 

Edited By Martin Connelly on 23/06/2016 17:39:19

Can you carve the solder away with a craft knife?

Martin

In an industrial environment the usual measuring tool would be a Bowers gauge. But these are too expensive a purchase for a home shop (I have a used 3/4"-1" that I got for free). How are you controlling the temperature in your work piece and workshop to achieve such a tight tolerance? Michael G got it right when he asked how well can you measure it. These sort of tolerances require some idea of workpiece and measuring tool temperature. The range of n6 at Ø15 (+0.012 to +0.023mm) is the same as a 6°C change in temperature in steel. If your workpiece is heating up as you bore it it could cause bellmouthing that is measurable. Flood coolant would control this.

Martin

Roger, consider an ER32 chuck that fits in place of your current chuck. It can hold up to Ø20mm tools. This would allow the use of slot drills or larger parallel shank twist drills to be used.

I sometimes use a No. 2 morse taper ER32 collet chuck in my tailstock.

Martin

My metric micrometer is a Moore and Wright non-electronic digital, no problem with reading the lines but I do have other mics with too much clearance between the barrel and thimble resulting in the problems described.

With regard to accurate sizing and tight tolerances, these are the result of a need for interchangeability of mass produced parts or parts from different locations that need to fit together without further work when they are brought together for the first time. For most of us that means tapped holes need to be good enough for purchased bolts. Some holes need to suit purchased dowels etc. but often matching the second part to the first part is perfect whatever the size.

Martin

Jon has pointed out the problem with relying on this type of system. The ratio of the radius to the rack versus radius to the spindle is the problem. One may be seven or eight times the other. This means that the error at the rack is multiplied by this ratio at the cutter. An error 0.05mm at the rack may be 0.5mm at the cutter. You may be better off just picking up the x axis setting by some other means, you can ignore the y axis error as it will be negligible. A simple method of maintaining the x axis setting is to clamp a square to the table, mount an indicator on the head in contact with the square and set to zero. Raise the head and adjust x back to the point where the indicator reads zero and you have the spindle correctly set to carry on.

Martin

Train return ticket punch. The first leg of the journey the ticket was punched and the second leg the ticket was collected.

Martin

Mike, the usual way to use an inverter is to connect it directly to the motor. The controls are low voltage and low current connections on the inverter but can be operated by the existing switch in most cases. It just needs wiring up so that there is a connection made for motor run in one position and for motor run and reverse as well in the other. Once you have an inverter and its wiring diagram this should be easy to figure.

Martin

Do you have three wires connecting to the neutral terminal? If so then these can be taken off the neutral terminal and connected to the U V and W terminals. You need to use a meter or continuity checker to find the ends of the three windings, U1, V1 and W1. Then connect U1 to V, V1 to W and W1 to U. This sets the motor up for 240v delta. It then is just a case if connecting a suitable vfd or invertor to the U V and W terminals.

Martin

One of the pieces of software on Mary's site is one I wrote.

Martin

An alternative to the rod in the chuck key hole is a large Allen Key in the chuck. As long as you can close the chuck down on to the hex hand tight is enough.

Martin

If you are intending to use Mach3 then get a pendant with a mpg on it. You will not need to turn the steppers manually. There is also a risk of generating pulses of electricity in the electronics if you turn the motors manually with them connected to your controller, think magneto here. If you want to use handles give some consideration to an easy way to disconnect the motors.

Martin

Andrew, the sketch was probably not a good rendition of what was produced. The thread form was asymmetric with one side correct at 30 degrees and the other at 60 degrees due to the incorrect setting of the top slide angle. This would produce a 90 degree thread similar to a buttress thread.

Martin

Seems irony was lost here!

Martin

A 1:2:3 triangle is a very special triangle with internal angles of 180°, 0° and 0°

Martin

Hopper, a 30°, 60°, 90° triangle has sides of 1, 2 and square root of 3 (1.73), the hypotenuse is the side that is twice the base . Going across 5 thou for every 10 thou in gives an infeed angle of 26.56°. Since this is less than 29° it is probably fine but will cause more cutting on the right hand flank of the tool than a 29° angle. If you want to get nearer to 29° use 5.5 thou across for every 10 thou infeed. The 2:1 ratio works well for 55° Whitworth threads where you want an infeed angle just less than 27.5°.

Martin

Turned down shank on a milling cutter.

I have turned down the shanks of milling cutters using carbide tooling.

Martin