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Member postings for William Chitham

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

Thread: Best way to cut/turn a 75mm Disc from a piece of Aluminium Plate
23/04/2021 16:49:45

Plus one for trepanning. I have just done my first one in 6mm steel aout 3" diameter. I screwed a square piece of stock to a piece of mdf and turned it in a 4 jaw. Went right through from one side, centre and ring popped out without drama.

William.

trepanning.jpg

Thread: Parting Tool Holder
15/04/2021 09:21:51
Posted by Gerhard Novak on 13/04/2021 18:13:50:

Nice work, but I think you will miss the height adjustment. may be you could have a shim below if needed.

I like the touch with the producers name and year. Is it punched or engraved?

Brief use so far suggests the height is right but as you say I can always shim it if it needs to go up a bit. Can't shim it downwards though! If it turns out to be too high I can take a bit off the hook. The letters are very inexpertly done with a cheap set of punches.

W.

13/04/2021 17:52:50

I finally got round to making my first tool holder for my lathe. I bought the parting tool from Arc with the block that fits the standard holder and it worked ok but the extra overhang always bugged me so decided to make this based loosely on the type you can buy for Dickson style toolposts. I decided to make it to a fixed height since it is dedicated to a single cutting tool but if it turns out that some fine adjustment is necessary I can always put a screw through the top of the "hook". The main chunk is cold rolled steel, the hook and the clamping bar are silver steel - the clamp bar was hardened with torch and oil quench.

William.

parting tool holder 04.jpg

parting tool holder 02.jpg

parting tool holder 03.jpg

Thread: Remote Control For Mitsubishi VFD
08/04/2021 11:33:01
Posted by Robert Atkinson 2 on 07/04/2021 19:13:21:

No ,

Meant a 24V NVR, powered from the PC terminal and contacts to the safety circuit.

Beg your pardon, I hoped that was what you meant but my searches (24V e stop; 24v NVR; low voltage NVR) haven't turned one up yet. Could you point me in the right direction?

Thanks, William.

07/04/2021 17:30:01
Posted by Bob Jepp on 07/04/2021 16:19:17:

I had a quick look at the Mitsubishi manual for the FR E729S inverter. The wiring diagram shows details of the safety circuits which show dual inputs S1 and S2 for the safety stop. It is intended that each device in the safety system should be provided with two electrically independent contacts ( closed when safe and open when unsafe ). Each circuit ( PC to S1 and PC to S2 ) should contain one of the dual contacts in each circuit. The intention is that there is two identical safety circuits which normally operate together hence giving two chances of a safe stop - operating only one circuit ( such as in the case of a mechanical failure ) causes a lock-out until both circuits are opened.

PLEASE, PLEASE make sure that the principles are adhered to - they are there to keep us safe ( even if they are a little more difficult to understand and implement ).

So should I be duplicating the circuit and use double pole switches or is it more complicated than that?

William.

07/04/2021 14:50:39

Ok, just had an illuminating conversation with a chap at Inverter Drive Supermarket. By default the two safety channels, S1 & S2, are shorted to PC (24volts). Any interruption to that voltage on either of them will cause the VFD to trip and immediately cut output power (I think it can also be programmed to apply an emergency brake to whatever machine it is powering) once tripped it will need a reset before it will power up again. I haven't quite figured out the reset circuit yet but I'm going to experiment with the basic continuity loop idea. Obviously this could include any number of door switches, interlocks and big red buttons.

mitsubishi remote control v2.jpg

07/04/2021 13:18:48
Posted by Robert Atkinson 2 on 07/04/2021 12:59:26:

You could use a 24V no-volt release start / E-Stop module. These a re cheap enough. Arrange the guard switch(es) to drop out the no volt coil and one contact to the VFD.

If you mean a 240v NVR on the mains input to the inverter then I'm reluctant to do that because as I understand it it is bad practice (ie likely to damage the VFD) to stop it by cutting power on the input side.

I expect some external arrangement of switches and relays could work but I'm hoping that a simple continuity loop through S1 and or S2 will do the job if I can find the correct parameters to prevent restart when continuity is restored.

William.

07/04/2021 12:13:01

mitsubishi remote control v1.jpg

After using my Boxford with the original 3 phase controls for a while I converted it to single phase with a Mitsubishi VFD and have been controlling it with a little remote parameter setting unit ever since. The remote unit duplicates the controls on the front of the VFD and has tiny buttons so not ideal but has helped crystalize ideas of how I want controls to work. Main thing is I want to go back to a 3 way forward/off/reverse switch for the normal running but I want to have a push button controlled jog function. I think this should work ok and have worked out a wiring scheme shown here. On the Mitsubishi the jog function trigger can be assigned to several different terminals, I'm using RL here. I have the Mitsubishi manual and I think I can set all the parameters I need to get this to work, the thing I can't figure out is how to arrange safety stops. This needs to do two things:

1. Provide an "panic button" emergency stop.

2. Hook up the various interlocks to prevent running with covers open.

I think it should be possible to use the Safety Stop (S1 7 S2) terminals to do this but the manual only seems to describe using this with a "safety relay module". I think that a simple continuity circuit across these terminals will do the job but it also needs a reset function to prevent it restarting when offending door is closed if the run switch is left on - this is because the logic of the unit will be set to work with an "always on" signal to the start terminal (STF or STR). I hope there is a parameter setting to do this but haven't found it yet.

Have any Mitsubishi users out there any ideas about how best to achieve this?

Thanks, William.

Thread: Boxford Model C leadscrew half-nuts
03/04/2021 16:23:35

My greater concern is there is not much "meat" (as mentioned by another poster) to remove for a sleeve.

I'll bet there's enough! Looking at your first photo it is odd how the wear looks heavily skewed towards the bed side as if the nuts are not on the centreline of the screw. I'd say that whether you repair these or replace them you might need to do some fettling to line them up nicely.

W.

03/04/2021 16:08:34

I watched that video too - and was about to comment on it after responding to everyone's replies. Yes, it's a good video and is making me feel more confident about this as a solution. Didn't he use epoxy to fix the sleeve?

Haven't got there yet, now you've spoiled the ending! Boxford nuts might be more awkward to set up for the boring operation because of the levers but I think the the overall process looks very convincing. It might be handy to have a stub of leadscrew to help centre the nuts for boring.

W.

03/04/2021 15:58:10

Here's a pretty good video of a guy doing a brass sleeve repair on similar sized half nuts for a Craftsman lathe.

Youtube

William.

Thread: Component Suppliers - Recommendations?
30/03/2021 15:47:13

Great result form IDS, should have thought of them in the first place. Lady I spoke to not only answered my questions about switches but also knows the Mitsubishi e series manual inside out and saved me hours hunting down parameter settings. Rapid looks good too for the odds and ends.

W.

30/03/2021 12:50:02

Brilliant, thanks all.

W.

30/03/2021 11:40:55

I'm in the process of designing a remote control box for the VFD that supplies my Boxford but since the demise of Maplins (not to mention Tandy) I'm always rather at a loss where to look for components. I need the obvious things, some decent sized momentary push button switches, a linear pot, a couple of rotary selector switches etc and I expect it is all there on Ebay but I can't find just what I want. I find the full on pro suppliers like RS a bit bewildering, can anyone suggest a supplier with decent range of products that is a bit more hobbyist friendly?

William.

Thread: Any advice on how to cut/file a 45 degree chamfer on a 1mm steel sheet to EXACTLY 45 degrees?
24/03/2021 17:26:06

I've seen 3 chamfering devices recently on Instagram and Youtube by Oxtools, Robin Renzetti and Stefan Gotteswinter. They are all based on the same basic idea, a V block with a milling cutter projecting into the bottom of the V. All handheld, all look capable of consistent, accurate results.

Oxtools , Renzetti, Gotteswinter 1,

Also a different approach:

Gotteswinter 2

W.

Thread: Loctite For Delrin?
24/03/2021 17:09:24
Posted by Michael Gilligan on 24/03/2021 16:39:42:

For what it’s worth ... I have great respect for technical advice from Permabond

Thanks Michael, that's a really useful link. Just to clarify my original post, this is a hypothetical question that occurred to me on reading another thread. Sticking metal components together with Loctite seems to have become a common technique, I was just wondering if it could be done with parts made from dissimilar materials, eg Delrin/CI.

William.

24/03/2021 11:22:33

Reading Tim Stevens' thread on making a gear for a Colchester thread indicator it was suggested that he might turn down the splined hub of a damaged gear and make a new toothed outer to fix on with Loctite. It was also suggested that he might make a new gear out of Delrin or similar. I think these were separate suggestions but could they be combined? Would Loctite 638, say, stick Delrin to cast iron?

William.

Thread: Advice on Heat Treating
17/03/2021 17:20:15
Posted by Grindstone Cowboy on 17/03/2021 16:59:37:

For a DTI holder, would brittleness be a major issue anyway? Hopefully it's not going to be subjected to much stress (unless you knock it off the bench)

Obviously I will be knocking it off the bench with grim regularity like everything else! Impact shocks aside I think the most vulnerable bit in normal use will be the "ears" of the dovetail which will only be about 0.75mm thick and will tend to be spread by the force of the locking collar screwed up from beneath.

William.

17/03/2021 15:58:44

Sorry Tug, thanks for your informative replies but my reference to colour was just in terms of using it as a guide when tempering. I plan to cold blue these parts when finished, I have some Phillips bluing solution which works well.

William.

17/03/2021 14:41:10

Thanks for all the suggestions. I don't suppose I would ever wear them out if I didn't harden them but I am using the project as a way to learn new things and I haven't tried heat treating before so... I think I will go ahead and harden them then heat treat in the oven, not least because that will be an excuse to cook a pizza this weekend. In the oven is it a case of holding them at temperature for a certain time then letting them cool gradually?

Of course I might be remaking the parts as tonight's challenge is to mill the dovetail slot in the end of the threaded one with a home ground cutter.

William.

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