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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: Running a Myford in Reverse?
12/02/2021 06:54:06

Hi Chris, Guys,

[quote]A screw-on chuck, as on the Myford or Boxford type lathes, will always unscrew unless specially secured. I have had a chuck fly off when I accidentally knocked the Dewhurst switch lever over and threw the Myford into reverse.[/quote]

This can only happen on a machine with a three phase motor ! Switching to reverse whilst running forward will not stop the motor, it will just keep running. The single phase motor speed has to slow down enough for the centrifugal switch to drop out reconnecting the start winding.

Thread: How does this temp trip work?
12/02/2021 06:46:48

Hi Ian, Guys,

I've very recently seen a thermostat that uses what appears to be a ceramic strip with a printed on resistive material that heats up and causes the ceramic strip to bend and open a pair of contacts. Rated at 15 amps as well.

If you have ever opened a microswitch, the mechanism looks to be very similar, the ceramic strip replacing the phosphor bronze leaf as in the microswitch.

Thread: Electric motor for L C Mason's Small Lathe
11/02/2021 20:01:58

Hi Ricky, Guys,

An excellent source of small induction motors is the scrap yard ! I've salvaged many "Shower Pumps" that have seized up pumps but the motors have all been OK. The hot side pump usually leaks and lime scale build up causes them to seize. Very occasionally water migrates into the bearings, but they are common, cheap and easy to replace.

I've salvaged motors from 175 watts (1/4 Hp) right up to 900 watts, (just over 1.2 Hp). All have been two pole motors (2880 rpm). There are some that are universal brush motors, but you don't always find that out until you pull it apart. I tend to take those back to the scrappy after I've salvaged the useful bronze parts.

Thread: Running a Myford in Reverse?
11/02/2021 19:47:48
Posted by SillyOldDuffer on 11/02/2021 17:33:02:

And a common problem with screw-on chucks is they stick so firmly lathes are damaged trying to get them off!

Dave

That is why I made a statement about keeping the threads and register scrupulously clean and well lubricated.

It takes very very little in the way of dust, dirt or other debris to jam the threads.

Thread: How does this temp trip work?
11/02/2021 09:23:39

Hi Guys,

These thermal switches use a PTCR device to which is in series with the mains supply and the rest of the circuit to generate enough heat to keep the switch open as long as the mains is connected. There is no neutral connection as such.

The circuit path is through the on/off switch through the thermal switch, through the elements and then out to neutral. The thermal switch is still live when the heater is switched on and connected to the mains supply.

NOTE: The PTCR is often a black pellet of resistive material that heats the bi-metal strip.

Thread: Running a Myford in Reverse?
11/02/2021 09:04:54

Hello Martin,

I too have a Myford S7 with a screw on chuck ! I have never had a problem with it unscrewing whilst threading in reverse. In fact I try to do all my threading away from the chuck. It is also the best way to do internal threads as well.

I do know of one chap that managed to unscrew his chuck, but that was his mistake trying to part off from the front with the tool upside down, jamming the blade in the cut.

A properly tightened chuck should not cause a problem.

A note on jammed chucks: Always make sure that the threads and register are scrupulously cleaned and oiled each time you change the chuck. It doesn't take much to cause a jamb !

Thread: Split Collet in blind hole
05/02/2021 20:29:27

Hi Peter, Guys,

The way I would make that split cotter is like this.

Drill a hole say 10 mm deeper than the collet length with a tapping size drill say 5 mm for an M6 thread.

Open out the hole to the collet diameter for the length of the collet.

Thread the 5 mm diameter in the bottom of hole.

Drill the collet right through 5 mm tapping size for M6

Drill one half of the collet M6 clearance, and thread the other half M6.

Thread an M6 screw into the collet and screw the whole lot into the bore.

Tighten up so that the collet is locked in the bore.

Then mark out and drill the cross hole making sure that you leave a mm of clearance between the outside of the M6 collet through screw.

Disassemble and clean.

Cut the collet in half by either sawing or parting.

Make sure that you properly deburr the edges of the scallop after parting in half.

If you do it properly it will take a quarter of a turn or less from loose to locked solid on the shaft.

15-09-2018-013.jpg

Here is one I made for my Norman Patent tool holder.  12 mm diameter, M6 through screw.  Note the edges at the bottom of the scallop.  Any burrs will cause those edges to dig into the bar that its clamped onto and make it hard to loosen.

 

Edited By John Baron on 05/02/2021 20:39:24

Thread: Myford ML7 4 way tool holder
23/01/2021 09:23:39

I agree with Hopper, the screws are counter sunk ones ! Since I no longer use my Myford four way tool holder any more, I've removed it and not missed it at all.

Thread: Advice for a newbie on tools and tool post for a Myford super 7
23/01/2021 09:18:29

Hello Mark,

I own and run a Myford S7B. I'm a great believer in making your own tools. I made the "Norman" patent tool holders for my lathe including a rear tool post. Drawing & Pictures in my album !

I bought a Dickson tool holder quite some time ago but found it far too expensive as a hobbyist to keep buying tool holders, so I sold it and made the "Norman" one. I have no problems setting the tool hight, no looking for shims any more as I had to do when using the original Myford four tool holder.

As far as grinding my own tools, I only use HSS and sharpen them as needed. The only insert tools that I have are threading ones. It is far more convenient buy and to use those than try and grind the angles for 55 and 60 degree threads.

HTH.

Thread: testing stepper a motor
02/01/2021 19:32:12

Hi Guys,

I must agree with the comments ! In nearly 50 years of doing electronic/electrical equipment repairs of one kind or another, I've never seen an electrically failed stepper motor ! Bearings, wear and seizing up, are the most common failure followed by the driving electronics. Ones that get electrically damaged are usually down to people playing about with them without understanding what they are doing.

Thread: Grenfell
23/12/2020 14:42:26

I can only agree ! But we keep voting them in...

Thread: engineering equipment/further reading
23/12/2020 14:39:08

Hi Toby, Guys,

Download a copy of the Presto "Counsellor" from www.presto-tools.com, link is near the bottom of the page. Its like a free copy of "Zeus" !

Edited By John Baron on 23/12/2020 14:39:21

Thread: Bit of Xmas Fun, Competition!
23/12/2020 14:34:53

Hi Martin,

OK I'll have a punt, links to fit door handles on each side of a door, the shaft goes through the door into the handle !

Thread: Stent Tool Grinder
23/12/2020 09:09:23

Hi Guys,

Peter asked me to put these pictures on the forum for him of his Collier Caseley. TCG,

001.jpg

002.jpg

003.jpg

004.jpg

Thread: Which Laptop
22/12/2020 22:11:04
Posted by Frances IoM on 22/12/2020 20:19:47:
there are 2 classes of HP machines - those aimed at the business market + priced accordingly which had + possibly still have a good reputation and those aimed at the bottom end consumer market which often seem designed to just make it past the warranty date - don't confuse these two markets.

Hi Frances, Peter, Guys,

I'm running a HP desktop machine, an 8300 small desktop model with an i7 processor, 12 Gb ram and 500 Gb hdd. I'm using Q4OS with the Trinity desktop. I agree with your comments about HP machine classes. I bought mine some time back as an "Open Box" purchase for £200. I'm very happy with its performance.

Thread: Stent Tool Grinder
22/12/2020 20:08:28
Posted by DiogenesII on 22/12/2020 16:29:15:

ER Tap Collets...

Weston Tooling ER Tapping Collets

Also available elsewhere I'm sure..

..I guess you'd only need to buy em' once..

Edited By DiogenesII on 22/12/2020 16:33:19

If you know someone with an EDM machine it would be easy to make an ER collet to suit !

Thread: Rewiring Li ion battery
21/12/2020 14:44:13
Posted by Alexander Smith 1 on 21/12/2020 13:06:50:

I was in Lidl last week and spotted a pile of 20v Li ion batteries at half price but there were no chargers. Being Scottish I couldn't resist as I've been thinking for a while about getting a new battery for a small circular saw which has a defunct Ni cad battery. I have several 20v chargers for Li iion batteries but they have different terminal configurations (using the + terminal plus another between the +ve and -ve terminals. This one has both +ve and -ve at the outside plus 2 other charging terminals in between. I've attached a photo of the battery with the cover off to show the terminals and the charging circuit. I assume that I just connect 20v DC across the 2 inner terminals to charge and use the outer ones to connect to the saw. Can someone with more knowledge of these things please confirm (or tell me I'm being stupid!) thanks.

Sandy sdc11207(1).jpg

Hi Sandy,

It all hinges upon how the battery condition/state is monitored and controlled. You might find that unless the battery circuit can talk to the proper charger it won't allow the battery to be charged at all, even though you may be able to measure the battery voltage at those terminals.

Take great care Li batteries can be dangerous ! Lithium can spontaneously ignite if it is exposed to air.

Thread: Stent Tool Grinder
20/12/2020 17:02:57

Hi Guys,

I've been building a modified "Brooks" TCG ! I will have been at it for two years come next March.

I've used ball races instead of the precision ground bars and made my own spindle design. If I was doing it again I would go the whole hog and use dovetail guides and gib strips. I've done a WIP on another forum along with drawings and photographs.

I'm now into things like control knobs, tool holders and assorted wheel hubs.

Thread: BCA jigborer motor
20/12/2020 16:28:07
Posted by Matt Mackeson on 20/12/2020 11:42:25:

Thank you all for the comprehensive replies. I don't think I have ever had such a quick and thorough set of replies to any post on any other forum!

I took the access plate off and found this handy wiring diagram for the two speed switch. If I understand this correctly the motor uses both star and delta for the two speeeds?

 

So it seems I have three options:

  • a new dual voltage 3ph with a VFD and adapter plate
  • a rotary phase converter
  • Look further into the VFD's posted by John. From what I understand this would give me a single speed on the current motor but then give me speed control through the vfd?

I am learning a lot about electric motors through all this so thank you all again for the help!

 

Hello Matt,

Unless I've misunderstood you, the motor would normally only be supplied from a single 380/440 three phase supply. The VFD that I pointed to, will behave in exactly the same way as any other VFD ! So yes you will have the ability to control the speed as you wish.

Only one caveat do not change the motor speed whilst under power. The VFD has to be switched off before changing speed by using the machines own switch. You will damage the VFD if you forget.

That motor will not run at full power on 230 volts even via a 230 volt single phase input VFD with 230 volts three phase output. You will still get the two speeds but only half or less of the HP.

HTH.

Edited to correct wording !

Re edited to add these VFD's are so cheap that the cost between 1 and 2 HP is very little.

Edited By John Baron on 20/12/2020 16:29:26

Edited By John Baron on 20/12/2020 16:32:23

20/12/2020 11:07:22
Posted by John Haine on 19/12/2020 22:10:49:

Hmm. If you read the overview it is slightly ambiguous. Many of these inverters can output 380V 3 ph if supplied from two phases of a 3-ph supply so the input is 380V, but of course with variable frequency. If supplied from 220V they only output 220V. This one doesn't really clearly say that it does give 380V output since one of the several input options is 380V. Over on eBay there are a lot of rather more expensive devices also from China that will only supply 380V with a 380V input.

Whilst that might be true for some devices it isn't in this case ! Its a straight 230 volts AC input and 380 volts three phase output. Yes there are some 380 volt three phase input 380 volt three phase output ones on there.

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