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Member postings for Simon0362

Here is a list of all the postings Simon0362 has made in our forums. Click on a thread name to jump to the thread.

Thread: Unimat 3 motor diode
24/11/2020 21:24:24

Thanks for all of the replies - the function of the diode is as suggested to half-wave rectify the inbound ac and to provide the lower of the two speeds. I have never seen a diode marked with a comma before, most of those I have come across have been in the 1N... series or similar. I will hunt down a replacement through our local suppliers.

Thanks also for the comments on the potential (pun not intended! ) causes of tripping - the Unimat is fitted with an XY suppressor, or was until I removed it when a similar problem appeared a couple of years ago - It gets very little use and I didn't quite get around to replacing it..... blush

The only remaining capacitive devices are a couple of small ceramics at the brush plate which I will snip out to test, hoping that the fault lies here.

There is no measurable line-earth resistance to the ability of my digital meter - given that the on-off switch also appears sound and the tripping happens on inserting the plug into the socket, I would expect a neutral-earth fault. Also, there is no smell of hot or dead windings which I know only too well, nor any visible signs of destruction - even if this not exactly a scientific test.

Tedious and the garage has become cold at night and work is keeping me occupied in my(warm) office during the day, so I have limited time to fault-find. Suppressors and diode on order in the hopes that the problem is not windings related.

I will report back when I find something.

Simon

23/11/2020 22:16:56

Hi All,

Trying to find the fault that is causing the "differentiator" to trip in our consumer box when I plug my Unimat into the socket has resulted in my terminally breaking the diode that allows low speed.

Can anyone identify this - or propose img_3364.jpgan equivalent that I can hopefully find from my Big Box Of Electronic Scrap

Thread: BANG!
23/11/2020 15:15:16

Many years ago I was trying to fault find a failing power connection which I traced back to the fused consumer unit. Checking using my newly acquired digital voltmeter across the switch revealed that apparently 220V existed but nothing was happening at the business end of the circuit. I then switched to the 10A setting and placed the meter in line which showed a few milliAmps were flowing. After digesting this a bit more I decided to check the volts again. Unfortunately I did this before returning the meter to a voltage configuration and promptly put a straight short across 220 V - the loud bang and flash left me stunned for a while, although fortunately neither I nor the house was harmed. The meter apparently was not reacting though since shorting the leads or connecting one directly into the other socket gave no visible readings. It turned out that both leads had gone open circuit, swiftly cured by a trip to Maplins.

Ever after, I have made a conscious effort to take a current reading and then return the leads to the voltage configuration.

I think the flash was my guardian angel briefly attending to me..... angel

Thread: Electronic Lead Screw Project
23/11/2020 09:29:41

Dennis,

Some thoughts:

  1. backlash through the encoder - so when you go from forward to reverse there are a number of missed pulses.
  2. stepper missing steps - maybe at the point of reverse direction, maybe during the screwcutting run or when returning
  3. noise into the encoder path
  4. since you keep the halfnuts engaged, I don't think the issue can be the config settings since errors here should only result in incorrect pitches/TPIs and not a loss in sync

#1 would appear to be most consistent with the reported symptoms - missing pulses to lose the sync between the leadscrew and the mandrel.

#2 again, I can only see this related to the change of direction at each end of the run. Any inconsistency during the cutting run should be visible as a lack of parallelism between the first and second cuts.

#3 same as above...

I can run my ELS by turning the mandrel by hand so in your case, I would:

  • put a long throw dti on the bed/saddle junction to see how much the saddle moved when I moved the mandrel by a full turn
  • observe the effects of reversing direction

Both observations may shed more light on what is going on and turning the mandrel by hand will also eliminate your motor as a noise source.

Also, check that the various 0V connections are not linked - in particular, the Launchpad 0V and those for the stepper driver - including screen path connections.

Hope this helps, I have had my ELS running for a couple of weeks and it is really good once it is running.

Simon

Thread: Unimat boring head
20/11/2020 09:10:32

Hi Gray,

PM'd you.
Regards,

Simon

19/11/2020 09:38:04

Hi Gray,

I thought Rex Tingey did something as well - but I have his book "Making the most of your Unimat" and it is not in there, although I vaguely recall that he wrote others.

The modified Unimat topslide was the first one that I found - written by B.R.Davies in 1980. The article that describes the one that I (partly) built was found by Michael and published in 1982. I eventually found another site where someone had copied the article into a pdf, so I now have the drawings and instructions. I am slightly awed by my (over) confidence some 38 years ago!

Regards,

Simon

17/11/2020 16:55:35

Michael, you have hit the money - as usual!

Certainly as far as the 1st page is concerned anyway, not having an account at scribd, I cannot see the rest of the article either.

So issue of 4th June 1982 and the 2nd July 1982...

17/11/2020 14:45:04

Thanks Michael, I had rather expected you to respond with a full reference and background...... wink

I couldn't initially find any reference to it in ME indexes but that was using my iPad which is a bit user hostile in those areas.

My PC has come up trumps (am I allowed to mention that name?) with a reference to A Small Boring Head for the Unimat 3, written by B.R.Davies in 1980 (v146, n°3644)

Neil, how about a reprint on the website.....?

16/11/2020 09:07:53

I have no desire to hijack Gray’s thread and the stunning boring heads that he has designed and built, however it prompted me to look out one that I started some time back.

I believe that the design would have been published in the early 1980s and was designed for the Unimat. As may be seen, the design used the rotation of a concentric ring to mesh to a gear that moved the boring tool holder, eliminating any other external adjustments. As can be more clearly seen, this was at the limits of man and machine at the time, especially man! The best thing about it was the knowledge gained in all sorts of ways including making gear cutters and cutting what looks like a sub-0.5mm pitch thread. I have also learned to break the edges on machined items in the intervening years, my fingers can confirm that this was not the case when I made the head.

It all came to a stop when the combination of minor errors finally culminated in an inability to continue. It has lain in my Unimat box of bits ever since.

Size can be imagined from the 5mm squared paper that the photos use as a background, roughly 40mm OD.img_3356.jpg

img_3355.jpg

img_3357.jpg

img_3359.jpg

img_3360.jpg

img_3362.jpg

I wonder if anyone else remembers this design – and could refer me to the original drawings?

Simon

Thread: LED Constant Current Source Scheme
10/11/2020 14:19:07
Posted by Joseph Noci 1 on 30/10/2020 07:31:08:

How many here have even considered any of these routes when you wanted a LED on/off indicator on your lathe/mill/clock/whatever??? Just stuck in a led, a resistor and found some source of non-lethal voltage, ignored the heat soaked resistor, and got on with it!

Joe

my solution every time....!

Thread: Virtual Meet Ups
04/11/2020 11:40:06

+1 please Neil

Thread: Tormach style tool holders
21/10/2020 10:41:36

Hi All,

I recall an article on making Tormach style toolholders for a CNC mill, possibly to fit a 'real' holder, possibly to fit a bespoke version. However, I am unable to find it and searches using key word like toolholder tend to produce a flood of responses.

Can anyone recall the article that I am looking for?

Regards,

Simon

Thread: ECAM v4 Lathe & Mill
20/10/2020 14:42:14
Posted by Emgee on 20/10/2020 10:48:20:

Plenty on this link to teach yourself eCAM, both turning and milling operations covered.

**LINK**

Emgee

Thanks again, I failed to see this section on their website - helps to understand what the capabilities are!

Simon

19/10/2020 17:00:52

Martin, that's really great, thanks very much.

My failure was to understand that the face milling operation brings the material to z=0 for all subsequent operations - I had assumed that it was another standard operation starting at a nominal z=0 and descending negatively from there onwards.

All slightly academic since my 48V supply abruptly developed a live-earth leak that trips our ELCBs and is measurable on a meter......a replacement is hopefully on its way as we speak.

I already really like eCam though, its great for the sort of rapid "mill a slot, three holes and a reference edge " that my preferred CAM (CamBam) is too heavyweight to swiftly generate this sort of actions.

BR
Simon

19/10/2020 09:27:57

Just stumbled across ecam V4 and highly impressed so far.....however there are obviously some things that are either bugs or (more likely) my failure to understand what I should be doing - for instance, I was trying to do a face mill operation yesterday and the parameters seem muddled - setting a depth of cut appears to do nothing, the only roughing feed applied is the finishing allowance...

Has anyone found a users forum or somewhere where I can pose the more basic questions that don't seem to be available through the site?

BR
Simon

Thread: Virtual Meet Ups
15/10/2020 09:26:49

+1

13/10/2020 22:26:54

Great idea, will join if I can.

Thread: Electronic Lead Screw Project
10/10/2020 13:42:06

If it helps anyone...I have modified the lid to make the electronics board integral with the lid itself and changed the attachment method to screws tapped into blind holes from the rear of the board, removing one set of bolts from the front.

On Thingiverse at: **LINK**

Simon

Edited By Simon0362 on 10/10/2020 13:42:39

Thread: Problems reading from a 3.5" floppy disc
23/09/2020 17:21:01
Posted by Emgee on 22/09/2020 10:32:53:

I know exactly where Greensands is coming from, I still use 3.5" floppy discs for a Denford Orac cnc lathe, the program and working files are all in DOS and I do have copies on the computer hard drive running with WinXP, further copies are on a memory stick that I use if writing a program for the lathe in the house.
The computer used in the workshop is disabled from connecting to the net for obvious reasons.

I do not have to use floppy discs but IMO why change something that's working.

Emgee

I spent several years developing and replacing disk drive emulators to replace the mainframe/mini 14" and 8" hard drives which ran process control systems - steel works, food processing, satellite tracking, oil refineries...the processes worked perfectly, the computers worked perfectly, the drives just wore out and were not replaceable.

Searching for "arduino floppy drive emulator" produces a number of options using some modern form of media combined with Arduinos or others to emulate the drive signals and to stream the data in the required MFM format. If you want to spend some money, I worked for the original founders of this company that still advertise replacement drives for floppies as well as a range of elderly and obscure drives. Solid State Disks Ltd

Thread: French model Engineers
07/09/2020 17:03:27

I missed this thread first time around but let me add myself to the French based list - based just north of Aix en Provence (13760) for the last 5 years, been in France permanently since 2007.

Apart from meeting up with Raymond a few times at his local exhibition and in contact with the small local group run by Jacque Maurel, VAP (Vaporistes Amateurs de Provence, https://vaporistesprovence.tumblr.com/), I know of no other light/model engineers in the region.

Pretty self contained here but would be happy to hear from anyone local.

BR
Simon

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