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Member postings for AJAX

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

Thread: Best way to run 400v 3ph motor on 220v
21/06/2022 19:03:15

Jak2g,

My Eagle surface grinder came with a 440V motor that was hard wired star configuration. After a test run using a 240V VFD I stripped the motor down and dug out the star point from the windings. I then rewired in Delta configuration. It was a relatively quick and easy job.

I'm not the only one to have done this. Whereabouts are you? Someone may be able to assist.

Thread: Car boot gizmo identification?
19/06/2022 10:50:37
Posted by MichaelR on 19/06/2022 09:14:12:

Steve, Haven't a clue what the first item is, but when I was serving my time as a joiner in the 1950s I would have given anything to own a Disston D8 Rip Saw or any Disston saw, but Disston saws were pretty unobtainable in those days, you have a valuable original tool in that saw.

MichaelR

There is a listing on eBay. 4 x Vintage Disston D8 saws for £40, including postage.

Thread: Looking for help valuing two lathes
16/06/2022 22:54:05

Chris, I've sent you a message. It should be in your Inbox.

Thread: motor insurance rant
15/06/2022 22:10:41

This might be of interest

https://www.freemotorlegal.co.uk/

 

Edited By AJAX on 15/06/2022 22:10:58

15/06/2022 22:07:51

Received a renewal reminder from RAC Car Insurance this week.

Last year's total = £115.25

Renewal price = £213.39 !!!!!!!!!

I tried to cancel online but was unable to do so. You can renew online (with no interaction) but to cancel you have to contact a customer representative.

I've changed insurer.

Zenith Insurance. Fully comprehensive. £0 voluntary excess. £109.54

Thread: Fortis Vice
09/06/2022 17:10:56
Posted by Rockingdodge on 09/06/2022 09:32:36:

AJAX,

Nice one, how did you restore it to it's current state, wire wheel?

Do you plan to make jaws for it to use?

Roger

Yes, wire wheel on an angle grinder. The surface rust cleaned of easily. It was then wiped over with an oily rag (hence the slightly gloss finish) as I have no plans to repaint it now. I did one small repair/modification to make the quick release work correctly, and I will make some jaws when some suitable scraptonium comes my way. For now, it's just sitting under a bench.

08/06/2022 19:39:06
20220512-210155 20220512-210146 20220512-210206 20220512-210211 20220512-210227
08/06/2022 19:38:29
Posted by Rockingdodge on 08/06/2022 17:58:20:
Posted by Jon Lawes on 08/06/2022 17:08:17:

My previous post I think got lost. I was pointing out that wartime equipment was often unpainted or blackened to save paint for the war effort.

I think you could be right as there seems to be no sign of paint but it's not that rusty, what I thought was heavy corrosion could well be an as cast finish!

I'm another owner of a Fortis Steel vice (pictures coming soon...) and although I cleaned it up a while back I don't recall there being any paint to remove. And mine is "Ministry of Supply - Property of HM Government" if that helps indicate the age.

Thread: Denham Lathe Restoration
07/06/2022 22:43:15

The "motor date" probably refers to the British Standard, bss170:1939 and not the date of manufacture.

Thread: Powering a Suds pump?
07/06/2022 10:35:52
Posted by Andrew Tinsley on 07/06/2022 10:19:07:

Found another 6 microfarad cap so using both in parallel gives 3 microfarads. This works a treat, so thank you Andrew Noyes! It gives almost perfect balance, using my scope (unearthed for this measurement!)

The tank and pump are stand alone items, to be switched to whatever machine is in use, so single phase is the best bet.

Thanks everyone for their input.

Andrew.

By placing two or more capacitors in parallel you are effectively increasing the plate area and so increasing the effective capacitance. When placed in series, you are increasing the distance between the plates and this reducing the effective capacitance.

Thread: Review prejudice - who do you trust?
03/06/2022 07:21:21

The worst reviews of all are the sponsored Vine reviews on Amazon. Don't trust them!

Thread: More beginner questions
31/05/2022 11:55:42
Posted by Andrew Johnston on 30/05/2022 20:44:52:

First things first; if you don't know what the metal is then bin it and get a known grade of metal. The ideal would be EN1A leaded. If, with a known grade of metal, the finish is still poor then the tool shape and position can be considered.

Andrew

I disagree with the comment to scrap it just because it's an unknown grade. Quite often, I and many others find a use for bits from the scrap bin. If he can't turn it with a reasonable finish now, put it to the side. He may be able to do so when the lathe and tooling is sorted.

I agree with the suggestion of trying some EN1A Pb. Aluminium alloy such as 6082 is another option.

Thread: What does this circuit do ?
26/05/2022 22:38:29
Posted by SillyOldDuffer on 26/05/2022 18:24:55:

10,000uF is a lot of capacity to put on an existing DC supply and is unnecessary if the diode is only there to protect against a reversed connection.

What 10000uF would usefully do is a basic smoothing job on the choppy DC that comes out of a car battery charger and many simple transformer wall-warts. It would even sort out an AC input. I expect that was its purpose; providing some reasonably smooth DC.

The fuse ought to be on the input side. As is, if the 10000uF capacitor shorts out, as electrolytics are prone to do, then the capacitor will go pop, possibly blowing the rectifier and igniting the unfused cable too.

Dave

I can't quite read the capacitor markings, but it may well be 1000uF and not 10000uF (10mF).

I agree with your comment regarding fuse on the supply side, but if the capacitor is large there may be an inrush current sufficiently large to blow the fuse.

26/05/2022 17:20:01

The circuit is a half-wave rectifier with capacitive smoothing, but in this application (DC supply) the diode protects against reverse bias and the bulk capacitor improves load regulation by reducing ripple.

The open circuit voltage should be around 0.7V greater than the output voltage under load. Consider the IV characteristics of the diode to understand why.

Thread: mini grinders
19/05/2022 20:20:45

I use one of those pencil type air die grinders. Cheap ebay job. Works really well, and I've given it some abuse. 30 to 50k rpm if I remember correctly. Doesn't use much air at all.

Thread: T-slot cutter
19/05/2022 20:16:49

I'm always interested to see simple homemade tools that work.

Thread: Myford ML4 change gear modification
16/05/2022 19:29:49
Posted by Georgineer on 16/05/2022 18:02:17:
Posted by Nick Clarke 3 on 16/05/2022 07:44:59:

A reminder that the original Drummond/Myford pins were tapered and only fit from one side.

I would be tempted to not do this with your new pins but use parallel pins held in place with loctite or similar.

I can't answer for the Drummond (though I have my suspicions) but the Myford used parallel pins of 3/32" silver steel. I have this in original Myford paperwork somewhere. Not Loctite - you want to be able to remove the pins, so nothing tighter than a sliding fit. .

The Myford way was to drill blind holes in the gears and collars, which trapped the pins in place. If you drill through-holes, the pin will work its way out and let go in the middle of a cut. Don't ask me how I know.

Ajax, I have used the pin drive system on my father's and then my own ML4s for over fifty years and it never caused the least problem that wasn't of my own making (see above!).

George

George (and others) thank you for the information.

It appears the consensus is to use pins and holes and not to bother with keys. I'm happy with that as it's the easier option.

I have some low-strength Loctite (about 6 unused bottles if I remember correctly!) so I will probably use parallel pins and the through-hole option.

16/05/2022 19:22:53
Posted by Bill Davies 2 on 16/05/2022 11:07:17:

Ajax, assuming that you would want to key the intermediate gears, they would have to have bushes with a key, through each pair of gears, to bear on the non-rotating shafts on the banjo. There would seem to be little benefit in keying the final gear to the leadscrew, if the previous gears transmit their power via pins.

Bill

That's another consideration. Thanks.

15/05/2022 21:43:39

I recently acquired a Myford ML4 which came with a limited number of change gears. The final driven gear has an unused keyway, and the leadscrew is not keyed (it has a small flat) and relies on a bush (fixed with a setscrew on the flat) that has a small pin that engages with the side of the gear wheel. All the torque is transferred via this small pin. Maybe that's a good idea, maybe not. I would expect it to be a likely point of failure in the event of a crash.

I happen to have a collection of keyed Myford change gears that could easily be modified to work on the ML4 lathe by adding a small hole for the pin. However, I'm wondering whether it would not be more sensible to mill a keyway slot and fit a key to the leadscrew. By making this one modification I could then use any of the change gears at my disposal.

I would welcome comments.

Thread: Boxford AUD/BUD single phase conversion
10/05/2022 18:59:07
Posted by Kingofthehill on 10/05/2022 18:50:18:
Posted by Richard Millington on 10/05/2022 11:25:57:

Check the motor can be wired Delta 240v.

The rating plate suggests that it can be. Suppose I won't know for sure until I pull it out of the cabinet and have a look.

If it turns out to be hard wired star, don't immediately reject the motor. I recently rewired such a motor by digging out the star point on the windings. It wasn't difficult to do.

Regarding all the existing switch gear, I would ditch the lot when fitting the VFD. A modern rotary or toggle switch is easy to wire up for controlling motor direction.

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