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Member postings for John Baron

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

Thread: Motor control board
09/03/2021 07:16:54
Posted by Keith Matheson on 08/03/2021 21:15:20:

Thanks for all the suggestions and guidance so far. Gratefully received. It makes problem solving soooooooo much easier and less time consuming - and hopefully less expensive. Anyway, onto current matters. I took the brushes out of the motor and found one broken in two (with the associated wire unattached) and the second looking somewhat short. I have found the same cross sectional area brushes on evil bay so have ordered a pair. I will report back what happens (I do so much hate a thread that doesn’t reach some sort of resolution)! I will also pop the new diodes into the previously died board and see if I now have a spare. Thanks again. keith MM ps like the idea of a pc fan attached to the motor housing- will do this as a sensible addition.653723ab-6aab-4f6a-841a-1f1f0c0451aa.jpeg

Hi Keith, Guys,

Thanks for the picture, that is what I expected to see ! just curious, did you measure the dimensions of yours ? I wonder weather they are the same size.

As far as the brush hardness is concerned there is no difference between AC and DC brushes, as seen in universal motor use. There are however quite marked different grades and composition of brushes intended for different applications. For instance, some brushes are copper loaded and some are very soft, like the carbon material that I am using for making my replacements.

I'm not saying that the stuff I'm using is correct, but it works for me. The wear on the brush is basically due to two causes, brush pressure and arcing. Higher pressure on the brush reduces arcing but increases wear hence the reason for harder brush material.

I would remove the brush cap and inspect the commutator for wear and blow out any dust. Inspect the wiring to the brush holders for any heating damage, particularly loose push on fix connectors. Any looseness will cause heating leading to failure of the insulation of the brush holder.

DO NOT attempt to remove the armature !

Apart from the fact that it will be very difficult, it will cause the field magnets to loose their strength.

HTH.

Thread: Home Made Rear Toolpost Issue
07/03/2021 22:04:35

Hi Dr_GMJN, Guys,

You could make a holder for the blade that clamps into the slot in the tool block and use shims under it ! There is no way I would want to start shimming under the whole tool post.

Thread: Motor control board
07/03/2021 21:59:51

Hi Keith,

Good question ! Those big brushes were given to me by a motor re-winders in Sheffield quite a while ago. They came out of their scrap bin. I haven't a clue what they would have belonged to, but they are enormous compared to the ones that I make from them.

06-03-2021-001.jpg

The one on the right is the one that I've made, it also requires cutting in half. That big brush is 50 mm by 32 mm by 6 mm thick. Manufactured by Morganite I believe. The brushes in the mill motor are 3.6 mm thick by 10 mm wide and 15 mm long. Everybody I've tried for replacements wants to sell me an expensive motor costing an arm and a leg !

07/03/2021 21:47:53
Posted by noel shelley on 07/03/2021 21:04:38:

No little copper wire down the middle of the spring to carry the load ? It might be worth wipping the mosfets or switching devices of the heat sink and checking them. Nothing ventured nothing gained ? Noel

Hi Noel, Guys,

No ! The little pigtails don't exist on my home brew brushes, they did on the originals, but they simply fell out allowing the motor current to destroy the springs.

Thread: Home Made Rear Toolpost Issue
07/03/2021 21:25:41
Posted by Dr_GMJN on 07/03/2021 21:09:16:

Ok thanks all. One way or another I'll retrieve it form the bin and give it one last go. Slot or top plate is the question. Top plate winning so far. I think I've got some plate that will do.

I think anything 3/8" inch or thicker will be quite satisfactory. Don't forget that the nut on top will also be adding to the security of the plate.

For what its worth, and I'm sure you have seen the picture of mine, I use a cheap Chinese parting blade that is 2 mm thick, 12 mm wide and 200 mm long. It is perfectly rectangular in section. And is clamped by two screws with a third used to clamp the supporting piece.

I don't have any packings or shims under the blade, the height of the whole tool block being used to set the blade centre height.

07/03/2021 21:00:14

Hi Dr_GMJN,

Just putting a steel plate on to replace the broken lip will not change the tool height or be any weaker than it would have been had it not failed.

You could of course do a much better job which would require far more work for very little benefit ! What I've and I noticed other suggested the same would produce a quick and easy fix.

Lets see piece of plate, five holes to drill four holes to tap. Two M8 two M6. Saw the top off, mill it clean, mark out for the five holes, drill. Tap the M6 holes, spot through the M8 ones. Drill 7 mm, thread the block M8. Fit the plate. Job done !  Opps forgot the hole for the long clamp screw.

 

 

Edited By John Baron on 07/03/2021 21:02:25

07/03/2021 20:37:55
Posted by Dr_GMJN on 07/03/2021 18:06:11:

So I milled the key to clear the new bolt:

and set it up using the "against the chuck" method suggested earlier in the thread:

I tried it on some steel, and then some brass. It was "OK", but in no way was the step change I thought I'd notice having read about the improvements to parting this should give. I thought I noticed some movement, so I went ahead and milled an extra slot in the block, for a clamp, which fitted perfectly:

I then tightened the bolts after setting against the chuck again, and...something felt wrong. Surely not a stripped thread?

No:



So, undeterred - for now - can anyone recommend a rear toolpost for an ML7, and also a good parting tool? Please don't suggest making one - I have less than zero interest in making tooling, I just want to buy something that works.

Don't mess about ! Just break that lip off, mill a flat across the top and bolt a steel plate on there to replace the broken bit. That failure is about what you would expect from cast iron. Use a pair of M8 coarse threaded bolts. to fasten the new plate.  Shouldn't take more than an hour !

 

 

Edited By John Baron on 07/03/2021 20:39:11

Thread: Motor control board
07/03/2021 20:17:37

Hi Keith,

Before doing anything else check the motor brushes ! These very commonly give problems, sometimes damaging the control board.

I've just made a pair of new carbon brushes for mine simply because it stopped rotating when it shouldn't have.

06-03-2021-007.jpg

The removed brushes !

06-03-2021-003.jpg

The springs.

Note that this is the remains of the previous pair of brushes that I have made and the springs are ones that replaced the previous ones.

There are a number of issues with these motors all mainly due to getting hot !

 

Edited By John Baron on 07/03/2021 20:27:31

Thread: Ball Races and 'Brinelling' (whatever that is).
07/03/2021 20:06:09
Posted by Swarf, Mostly! on 07/03/2021 16:45:19:

Hi there, all,

Back in the days when I was in gainful employment, I had a colleague who was a mechanical engineer. He observed that ball races were/are intended for continuous rotaion and that if they habitually only rotate less than a full turn the races would 'brinell', damaging the bearing.

This comment interested me at the time because there was an advertiser in the Amateur Radio magazines who used to sell Morse keys with their beam pivoted on ball races - he claimed this method was superior to keys with plain pivots. (A counter opinion at that time was that the best Morse key was that made for the Royal Navy which employed flexure pivots. The RAF Pattern D Morse key employed a taper pin pivot. )

Nowadays, I occasionally dismantle the odd computer hard drive or two. These usually employ two sets of ball races, one set on the platter motor, the other on the read/write head arm. The angular excursion of the latter is only about 45°. The head arm is light but moves quite quickly so its bearings might experience relatively high stress.

I've accumulated quite a few of these ball races - do members think they are fit for 'normal' bearing duty or should I scrap them?

Best regards,

Swarf, Mostly!

Edited By Swarf, Mostly! on 07/03/2021 16:46:03

Personally I salvage them amongst other things and find them extremely useful. I rarely buy bearings but use ones that I can salvage and test. If they are noisy and feel even slightly rough, they get binned.

Thread: Locating a copy of a CDROM for a C Compiler
06/03/2021 19:34:12

Surely any Linux Live CD will have a copy of GCC on it ! Or Google "GCC Compiler"

Try

https://www.guru99.com/c-gcc-install.html

 

Edited By John Baron on 06/03/2021 19:36:33

Thread: Alfred Herbert high speed bench drill
06/03/2021 15:12:02

Hi Andrew,

The motor is 440 three phase ! But I recall a similar high speed drill that had an extra pulley, so you could swap the motor one. The motor was adjustable for distance to account for the change in pulley size. Might have been an Alfred Herbert one. If it is the one I'm remembering, the chuck only went up to 3/8", tiny little thing.

Thread: Help needed, can't release cast iron wheel
06/03/2021 15:01:54

Hi Guys,

You need to get the heat on the hub as quickly as possible before the shaft has a chance to start to get warm. Then the hub will expand before the shaft. It should come off after that.

Thread: water level sensor
05/03/2021 21:14:32

Hi Duncan, Guys,

An old computer mouse will provide you with at least four IR pairs. Two on either side of the slotted wheel !

Thread: ER Collet choices
05/03/2021 09:00:32

Hi Guys,

I tend to agree with Jason, I bought an ER32 collet chuck for use on my mill, I also have the one that was supplied with it. Both chucks come almost level with the bottom of the perspex guard/shield. So without removing that shield it effectively limits the amount of stick out of the spindle.

So whilst I agree that MT3 collets fitted directly in the spindle will give you more headroom you would have to remove the shield to take advantage of the extra clearance.

Thread: Free 3D CAD files (ER Collets)
05/03/2021 08:50:29

Hi Guys,

I seem to recall Chronos do or used to do an ER32 chuck that just screwed onto the Myford spindle nose.

Expensive though, I do recall someone describing how they made their own.

 

 

Edited By John Baron on 05/03/2021 08:50:50

Thread: Home Made Rear Toolpost Issue
03/03/2021 17:57:00

Hi Guys,

I perceive one problem with all the rectangular rear toolposts !

That is ensuring that the tool is dead nuts parallel to the chuck ! Any slight miss alignment in the positioning will cause parting issues. Here I'm talking about angular and or rotational alignment.

Thread: Groups io browser operation
03/03/2021 17:41:58

I remember from the "Dial Up Modem" days, the scammers would quietly change your access phone number so that you dialled a premium rate number to access the net. I also recall quite a number of instances where a users machine was used to store the intruders files and other nefarious items. But ensuring security wasn't as big an issue as it is today. I know of one hack that can gain me access to a Windows machine ! No I'm not going to say how, other than it worked right from W98, and still works in W10.

Thread: Newcomen Plans or kits - looking for.
03/03/2021 11:49:12

Posted by Chuck Taper on 02/03/2021 23:14:47:

Could anyone recommend a source for decent Newcomen Engine plans or better yet a good kit. There is some stuff out there but .... a bit wanting.

Ideally I'm looking for something that clearly illustrates the central principle & operation of the engine rather than a strictly historical recreation - not sure if I explain that clearly.

Thanks in advance for any help.

Frank C

Do these pictures help ? They are of a Newcomen engine in the black country museum, that still runs occasionally.

29-10-2017-047.jpg

29-10-2017-048.jpg

29-10-2017-049.jpg

29-10-2017-050.jpg

29-10-2017-052.jpg

29-10-2017-053.jpg

29-10-2017-054.jpg

I saw this engine running a few years ago when I first went to the Black Country museum. It was running last time that I went there.

Thread: Help needed to lift bandsaw curse.
02/03/2021 19:12:22
Posted by Bill Phinn on 02/03/2021 17:44:27:

Many thanks, Jason and John. Good to know this strange crop-circle-type effect has such a simple explanation.

Since this problem is with the second blade and the first is already known to be defective, I take it this means that both the blades supplied with the saw are a bit sub-standard.

Tuffsaws replacements beckon fairly soon.

Hi Bill, Guys,

Not necessarily defective, its far from uncommon, particularly if the blade weld is slightly out. More often you can bend a tooth just by letting the weight of the arm rest on the work when starting a cut. I've ripped teeth off forgetting to start the saw before lowering onto the work.

Thread: Home Made Rear Toolpost Issue
02/03/2021 14:35:24
Posted by bernard towers on 02/03/2021 12:23:40:

Hopper I thought that the two nuts on the foot went towards the operator, that’s what makes it so rigid!

+1

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