Member postings for Martin Connelly

If you are talking about the threads for tooling used in Clarkson Autolock and Vertex type Posilock then they all have the same imperial TPI but the diameter can be varied to suit either metric or imperial sized tooling. So you can have a Ø5/8" tool and a Ø16mm tool but they both have the same thread TPI. You do need collets that suit the diameter though. You should not use a Ø1/4" collet for a Ø6mm tool.

This is a Ø16mm ER11 collet chuck with the thread cut to the same TPI as a Ø5/8" or a Ø1/4" end mill.

Martin C

A material that will remain non-magnetic is always preferable to something that can stay magnetic for a long time. This is a good reason to use cast iron over mild steel, it is easier to clean up small steel particles if they are not attracted to a magnetic lump. How does it become magnetic, stick a magnetic base for a DTI on or near it is all it takes.

Martin C

I use a continuous low pressure 12V blower to just move the chips a small distance away from the cutter when using carbide without coolant. I also have an electric hand held duster/blower for blowing more than the blower but less than compressed air. Very rarely switch the compressor on.

Martin C

I am assuming this is done with power feed and that the lathe you have uses the leadscrew for this.

Does the ripple spacing match the leadscrew pitch? If so there is a possibility the leadscrew is bent or something connected to it is out of position or badly made. By badly made I mean something like a gear with the bore slightly eccentric. A bent leadscrew should be visible, gearing in the carriage is harder to spot and fix.

If you change the feed rate and the pitch of the ripples change it points to something in the change gears/gearbox.

A bent leadscrew will move a carriage around if the carriage gibs are not set correctly and produce ripples like this but I have had something similar but not feelable from one end of the leadscrew running slightly eccentrically.

Martin c

Looks good, no need to redesign something that works when you can just use different materials and modern manufacturing methods.

I have never had enough need for something like this so I use the felt method. Place the sheets down on a thick enough layer of strong felt, open the stapler out and use it to put the staples through the fold and into the felt. This does not fold the ends over so you just do that part by hand with a steel rule. Some carpet types also work instead of felt. Not good enough for professional results but fine for the odd personal job.

Martin C

Often lathes supplied with a 127 tooth gear are partnered with a 120 tooth gear and have simple pins to transmit the drive. I would expect that if this is the case the 120 tooth gear would have splines and the 127 tooth gear to be clearance. Having both gears splined may be more costly than the pin drive option.

Martin C

The external switch circuits are low voltage (12V) so I would just connect a wire to the ground terminal and touch the Run terminal with it to see what happens. If it only runs when the wire is connected then a normal on/off switch will work as you want. A second wire from ground to the Rev terminal should confirm that a forward/reverse switch will work the way you want as well. This is assuming you have set the parameters for an external switch.

Martin C

I will just add that for machines using a VFD they usually stop faster if the VFD is still powered up and the VFD is set to stop with a rapid ramp down and a braking resistor. It works like the DC brake now required in industry. Cutting power allows the motor and whatever is connected to it to coast to a stop without any active braking. This is why an emergency switch for a VFD powered machine needs to set the VFD to stop rather than cut power to the VFD.

Edited By Martin Connelly on 17/02/2023 11:19:10

It looks like you have this VFD A2 VFD manual

The front panel has membrane switches so the unit is set up to start and stop when a membrane switch is pressed, you don't want to be standing there holding the switch down with your finger for hours. In order to use on/off switches you need to be able to change the way the VFD responds to an external input. Looking at the list of parameters this may be what settings Pn04 and Pn05 do. Setting an external switch for the run command (Pn04=2) and clockwise/anticlockwise enable (Pn05=3) could be what you need to do. Then an emergency stop would just require putting in series with the run/stop line to stop the motor but would not switch off the VFD. It should be easy to work out if this works the way you are hoping for.

Martin C

The capacitor/condenser in an ignition circuit is there to collapse the magnetic field in the coil's primary winding as quickly as possible. They balance the reactance of the coil with a 180° out of phase reactance of a capacitor to get a vector sum as close as zero as necessary for a good spark to be generated.

Martin C

There is usually only one switch for forward/reverse, open motor goes one way, closed it goes the other. Then a second switch can be used for run/stop as you require. This is the way I have my mill set up. My lathe is set to run forward or reverse from a single switch that is the original lever switch for the lathe.

On some VFDs you can select if the switches are latching or momentary. In most cases the VFD will not start the motor if the run switch is on when the VFD is switched, on as a safety measure. This means a simple on off switch can be used safely as the run/stop switch.

Martin C

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Martin C

It is a 400 volt (phase to phase) motor but it is likely your VFD puts out 230 volts (phase to phase). You can get one that puts out 400 volts but they cost more than the usual cheap options.

Based on wiring diagrams I have seen for 2 speed 3 phase motors the coils require 230 volts across them. However there are six coils with 12 tails and separating them then linking some to give six tails to enable the correct wiring for a 230 volt VFD looks daunting.

Normally the VFD should be connected directly to a motor and it is recommended to not disconnect a powered up VFD from its motor by passing it through any form of switch.

Martin C

Looking back at my post the line that reads The chip thickness will be 3mm / 60mm/s­ = 0.05mm should have 3mm / 60 cuts/min.

Martin C

Edited By Martin Connelly on 14/02/2023 11:49:22

RPM, locking up unused ways and machine rigidity are not the only thing that matter. In order to cut there needs to be a big enough bite into the workpiece from the cutting edge. Too small and it will rub the surface, too big and it will damage the cutter. To get a good finish requires a steady motion at a suitable speed. Anywhere where the tool is paused will be rubbed below the surface that can be cut. This rubbing is not good for either the finish or the cutting edge of the tool.

When someone refers to speeds and feeds these are the two factors that are being talked about. Speed is the rate at which the cutting edge is passing over the surface it is cutting and is calculated from the RPM and the diameter of the cutter. Feed is how fast the tool axis and workpiece are moving relative to each other. Feed is used to obtain a sensible cut each time the cutting edge engages with the workpiece. For example, if you have a single cutting edge on a tool rotating at 60 rpm and travelling 3mm per minute the tool will rotate 60 times in that minute and feed 3mm at the same time. The chip thickness will be 3mm / 60mm/s­ = 0.05mm. Two cutting edges on the tool will halve the chip thickness to 0.025mm.

Doubling the rpm of the single edge tool will also halve the chip thickness from 0.05mm to 0.025mm.

So, going back to the original problem, if you are using a feed rate that is too slow then there may be times when the tool is dwelling in one spot and rubbing. If you are using powered feed that is too slow the tool can go from cutting to rubbing to cutting. The chips that are coming off should give some indication of correct feed, you do not want very fine slivers, they should be discrete chips.

Another factor is tool flex. How much stick-out is there? A long thin tool will deflect much more than a short fat tool. A 3 or 4 flute cutter is more rigid than a 2 flute tool. Adaptors that extend the tool out from the spindle (R8 to ER for example) can increase the stick-out as well.

There is one other factor that can cause alternation between cutting and rubbing and that is the state of the bearings of the spindle. If you have a relatively new machine it is possible that the bearings have started to settle in place and may need adjusting to take up some slack. An older machine needs adjustment if the bearings start to wear. A simple test for correctly adjusted bearings is that they should get warm but not hot when working. So the question is, if you run the spindle at full rpm for about 15 minutes but doing no work with the machine do the bearings at the top and bottom of the spindle get warm to the touch, stay cold or get too hot to touch. Warm is what you want. Frequent need to adjust the bearings means they need replacing.

Martin C

Edited By Martin Connelly on 14/02/2023 08:58:40

Nigel, I edited out the stop blocks comment just after I had written it, I realised it was the index mark at the top when returning to the pictures. I did this quite rapidly but you managed to spot this error and commented after the correction was made.

Martin

The lever looks like a brake to me that interacts with the rim of the table. The rim of the table looks like it has plenty of witness marks from the pressure. The lever behind the handwheel could be a brake on the handwheel. They do not look like they interact to me.

Martin C

Edited By Martin Connelly on 13/02/2023 08:38:28

Edited By Martin Connelly on 13/02/2023 08:40:14

If you had said which other machines it is similar to, such as the Chester Super Lux, you may have got more responses. You have not mentioned if it is fitted with a powered X axis drive or a DRO, both of which make using a mill much easier. A more powerful mill with larger table travel requires a lot of hand cranking and, if you are planning to use multi-insert facing mills, a lot of fast cranking. The longer travel also makes losing count of revolutions of a handwheel a greater possibility.

I suggest, from experience of one of these we had at work, that the chuck guard will get broken off quite early on and will rapidly become disused due to the cost of repeatedly replacing bits of it. I also had to buy better knobs for the gear change as the ones supplied were not robust enough for use in an industrial department. I also think we replaced some of the ball knobs on the end of the arms for lowering the quill. I think one rattled loose and fell on the ball which was enough to crack it. We only used it for drilling gland plates for junction boxes using mainly annular cutters and a few step drills for plastic boxes.

Martin C

I'm ambidextrous, I write equally badly with both hands. The subject of left and right handed versions of items has me puzzled sometimes. You never see right handed pianos and a lot of other instruments but you do get left handed guitars. If it was simply to a case of catering for dominant eyes then why this inconsistency? I went to my daughter's school for a concert and there was one trumpeter playing a standard "right handed" trumpet with his left hand. It looked crazy and I could not figure out why he did not learn to use his right hand when he first started.

Martin C

You could make some suitable pillars and mount them in a standard box. You may have to add a frame to ensure there is no gap around the edge.

Martin C

Do you have a travelling steady? This is the type of job they are for.

Martin C