Member postings for Les Jones 1

It is not recommended to do any switching on the output of most VFDs. I suggest that you check with the manual for the VFD that you have. You normally have the forward ,reverse and stop controls together with the speed control potentiometer mounted in a convenient position away from the VFD. The wiring between the controls and the VFD is only low voltage and current so thin multicore wire is used. It is probably possible use the old forward/reverse/stop controls connected to the control inputs of the VFD. using the old controls in this way may give problems as sometimes the contacts oxidise when there is no cleaning action that occurs when switching high voltages.

Les.

There should be nothing other than a length of 4 core (3 phases + earth.) screened cable between the VFD and motor. There should be no contactors or switches between them.

Les.

If the headstock is removable from the bed would it be possible to make a packing piece to raise the headstock by 3/16" ?

Les.

When drilling the holes in the cylinder cover do not drill them to the final size. (Screw clearance size.) Drill them to the tapping hole size. (Or smaller.).

Les.

You seem to be assuming that the cutting tip is level with the top surface of the boring bar. If you make your boring bar with the cutting tip close to the centre line of the boring bar then the diameter of the main part of the boring bar can be closer to the starting hole size.

Les.

Can you provide some information on the board ? As a TOTALLY WILD GUESS there is probably a power mosfet that does the switching of the motor current. Using a switch to short source and drain should work. (The switch will have to carry the full motor current.)

Les.

I did a similar thing using a a rotary table and a right angle drill adapter.

Les.

Is it not possible to draw them in using threaded rod, short lengths of tube and some thick washers ? It is over 50 years since I had an A series engine in bits so my best best guess would be that 6mm is about the largest threaded rod that would fit through the valve guides.

Les.

I agree with chrisB that your scales are the capacitive type and they will not work most display units as most of them expect quadrature signals which most glass(Optical) and magnetic scales provide. To make things more complicated there are a number of different protocols used with capacitive scales. There is one DIY design that works with some types of capacitive scales. This is a link to it.

**LINK**

I have not followed that project for a few years so I don't know the capabilities of the current version.

Les.

If you are planning to use it to try to remove the bearing I think it is not the correct grade. For that i suggest 638

Les.

The grade of loctite that I have used in the past is 638.

Les.

Try turning down the end of some threaded rod (10mm or above.) to a couple of thou under 8mm. Clean out any oil or grease from the hole in the bearing. Loctite the end of the threaded rod into the bearing and leave it for a day or so to set. Use a suitable length of tube and thick washer to draw the beating out. (I can't remember which grade of loctite is the strongest.) You can remove the threaded rod from the bearing using heat, Repeat the process for the second bearing.

Les.

Edited By Les Jones 1 on 10/04/2021 10:59:37

Although Howard's comment about slip rings is wrong (As it will not have slip rings) It made me wonder if it's 3 phase supply was derived from a static converter rather than being a true 3 phase supply. If it was then that MAY have some influence on the problem.

Les.

Edited By Les Jones 1 on 05/04/2021 17:39:39

You could try covering the rotor with engineer blue or a marker pen then run the motor in the direction that gives the noise. After it has run for a time you could examine the rotor to see if any of the marker has been rubbed off.
Depending on the design of the motor you could try rotating the end plates or swapping the rotor and end plates end to end. (If you try this make sure that the rotor would still be lined up axially with the stator.

Les.

I think Stuart Smith is probably thinking along the right lines. A thermal cut out (Or an intermittent connection inside the pump.) seems likely. It probably warms up and the contact breaks. It then cools down and the contact re makes.
It would be interesting to monitor the current to the pump to see if the current drops to zero when it stops.
I think a new pump will be the only solution as the ones I have seen are encapsulated in resin.

Les.

Edited By Les Jones 1 on 04/04/2021 12:36:34

Looking at your picture it looks like the casing is all plastic. I think connecting one side of the battery connections to the mill metal work may solve the problem. Just in case there is already some connection via metalwork that I can't see I suggest making the connection via a capacitor. I suggest about 100 nF but the value is not critical. Also it should not matter which battery connection you connect to. I think there is a removable cover to connections for a remote readout to the right of the battery cover. (As positioned in your picture.) There will be 4 connections. two connect to the battery. (You can check which these are with a DMM on the resistance range.) The other two connections will be data and clock signals. The battery connections under this cover are probably the easiest to make a connection to.

Les.

Possibly a rear roller from a cylinder type lawn mower.

Les.

Are the taps that give the problem fed from the high pressure mains supply that feeds the tank or are they fed from the output of the tank ? Assuming they are fed from the high pressure side it may be that the new ball valve has a snap action cut off rather than the type that gradually shuts off the flow into tank. I think Jon Lawes about air in the pipes acting as a cushion before the ball valve was replaced could be right. If so fitting a Hammer Arrester may solve the problem. (Search Toolstation, Screwfix, or plumbing suppliers for " Hammer Arresters" to find one.)

Les.

Hammer Arresters

From the link that old mart has provided check that you have set the parameters in table 11.1 on page 11 correctly.

Les.

If the saw blade was 80mm diameter then for the same cutting force the torque required would be 20 times as much as required for a 4mm diameter end mill. So if the saw blade was 2mm thick it would be like a 2mm depth of cut with a 4 mm end mill. I don't think I would attempt a 2mm depth of cut using a 4mm end mill on steel. To use the same motor you would need to gear it down by a ratio of 20:1 to increase the torque by 20:1
I agree with the other replies that the answer is NO.

Les.

Edited By Les Jones 1 on 05/03/2021 15:49:42