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Member postings for Tony Jeffree

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

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Thread: MEW 186 - Electronic Lathe Control
21/01/2012 17:41:07
Posted by Ian P on 21/01/2012 12:44:47:
Tony
 
I think I was rather hasty in focussing in on what I thought were weak points without thinking it through, I accept also that with precautions taken to overcome the shortcoming (back gear, low speed etc) threads suitable for almost everything other than feedscrews could be created.
 
Do either of the systems you describe have an option to use a shaft encoder with many more pulses per rev? Presumably that would improve the accuracy.
 
Ian P
Ian -
 
A shaft encoder would certainly be a better starting point, but neither device is capable of dealing with anything more than one pulse per rev unfortunately. They are both designed around relatively low cost, low (computing) power single-chip microcontrollers that simply don't have the processing power to handle a higher pulse rate (bear in mind that they would need to be able to handle the shaft encoder in addition to the existing one pulse per rev encoder, as the latter is used as an index pulse that indicates the start of a new rotation - even if you just increased to 2 PPR, you would still need the 1PPR signal as well). Interestingly, Mach 3 is also limited to using a 1 PPR encoder and suffers similar problems when the spindle speed is not stable. However, EMC2 can handle a shaft encoder and by all accounts gives good results even with relatively low counts per rev. There is a Youtube video that shows a Myford lathe being turned by hand & the EMC2 software is handling it perfectly: http://www.youtube.com/watch?v=AW5-A_ru3-I
 
Regards,
Tony

Edited By Tony Jeffree on 21/01/2012 17:43:10

21/01/2012 11:38:36
Posted by Ian P on 21/01/2012 09:14:11:
I'm with Billy on this one!
 
I had been aware of the term 'ELS' for many years but never investigated the forum. I just assumed it was a leadscrew only version of CNC conversion and it never got my attention.
 
I cannot imagine anyone would spend so much and go to so much trouble to cut a thread by such a flawed method. Even if the pitch was accurate enough for the job in hand, techniques like cutting a thread close to a shoulder would be fraught with difficulties.
 
I am slightly surprised that the author, a knowledgeable and skilled person could consider that this was a viable alternative to a full CNC system.
 
Ian P
Ian -
 
I am slightly surprised by your (and Billy's) reaction - it makes me think that you didn't read the article fully.
 
Firstly, ignoring the screw cutting for a moment, the two devices described are very definitely a viable alternative to a full CNC system for some uses, and likely a good proportion of the uses that the average hobby user would want from them. And for many, the fact that these are self-contained devices that don't require any knowledge of PCs, G-code, CAD/CAM, etc. make them doubly viable.
 
Secondly, as I pointed out in the text, the screw cutting capability can be used to cut acceptable threads, within the limitations of the stability of your spindle speed and the one pulse per rev encoder. If I put my ML-7 into back gear, the increase in torque at the spindle is such that the spindle speed is rock solid, and it cuts threads just fine. In reality, on my lathe, with its 1/2 horse motor and V-belts, putting it in back gear is pretty much a requirement for threading anyway, to avoid motor stalling and/or belt slip.
 
Thirdly, cutting up to a shoulder is rather easier with one of these devices than it is under manual control, and no less easy than under full CNC, because the controller stops the saddle feed at exactly the right point, retracts the cutting tool, and returns to the start point for the next pass, with precise repeatability.
 
Regards,
Tony

Thread: MEW 186, Best ever issue
21/01/2012 11:20:57
Posted by Stub Mandrel on 20/01/2012 21:13:34:
Perhaps the answer is simple -
 
Allow site users to share files other than jpegs, and announce that you don't want to put code in the magazine, but if anyone is willing to share their code online to accompany an article, they can do so here.
 
Either it will work or it won't.
 
I for one don't have any CNC files but if I had a place to share them I would probably crteate a few simple utilities in BBC BASIC or as excel spreadsheets that I would happily share here.
 
For example, i a few folk have asked me for advice on bevel gears- I could describe my method in an article, and put a calculator spreadsheet up on the website to go with it.
 
Neil
 
I agree.

There's absolutely no point in putting G-code in the magazine unless it is part of an article describing how to code in G-code, in which case it would only be short fragments to give examples. Apart from anything else, the thought of typing in a G-code program, and then fixing the numerous transcription errors that you would inevitably make, is too horrific to contemplate. So publishing G-code programs on paper is a complete waste of magazine space and the reader's time. The only thing that makes any sense is to make programs available on-line somehow, or maybe for the author to offer to email the files to interested readers (I have done that in the past for MACH config files and for the code files for my rev counter, for example).
 
Regards
Tony
20/01/2012 14:45:46
Posted by Ray Lyons on 18/01/2012 18:41:52:
I remember some time ago, Tony Jeffree wrote in these pages that there is no need to learn G-Code. He said that using a CAD programme the drawing can be transferred to the computer for cutting.
 
I believe he was preparing an article on this for MEW which would be great for many of us trying to understand the system and could be a better way of introducing CNC
 
Ray -
 
I did indeed write that, and it is absolutely true. I have been using (and building) CNC machines for more than a decade now, and I have yet to find a problem that requires me to learn G-code, so I haven't bothered to do so. Not that learning it would be a problem for me - I started my working life as a computer programmer, and in any case, G-code is a trivial language for anyone to learn. It just isn't necessary for the vast majority of things that you might want to do with a CNC machine, assuming that you have the right software to start with.
 
On my two CNC mills, I run Desk CNC; this takes CAD files as input and generates the right G-code as output, so I never need to write or even look at the G-code. On my CNC-converted ML-7 I run Mach 3, which has a number of "wizards" that allow you to fill in boxes on the screen to define the usual turning operations (threading, plain turning, tapers, facing...) and again, Mach 3 generates the necessary G-code for me. I also use the ELS and Puttnam lathe controllers with the lathe (as seen in my article in #186) and those devices don't even understand G-code - you set up the operations from the keypad, a bit like (and no harder than) a pocket calculator.
 
I was indeed planning to write something about all of this, but as Martin (Blowlamp) seems to have got there first I will be holding off on that until I see what his article covers. The other aspect(s) of CNC that might usefully be covered are an overall introduction to CNC so that readers will have a better understanding of what the components of a CNC system are and how it all fits together. Sort of a dummies guide to CNC, which would help would-be purchasers and/or builders of CNC systems to understand what they need to buy/do. I have made a start on writing something along those lines but it may take a while!
 
Regards,
Tony
Thread: New Blocks on the Block
18/11/2011 12:23:58
Posted by John Stevenson on 18/11/2011 09:21:29:
JESUS H CHRIST ON A PUSH BIKE
 

John -
 
When 2 or 3 model engineers are gathered together, they shal find something to whine about. Ignore them - they are just talking blocks...
 
Regards,
Tony
18/11/2011 10:42:02
Posted by Chris Trice on 16/11/2011 22:32:56:
The disclaimer has always been pretty pointless in my view since how would you know the person making the claim wasn't lying? It's meaningless. It's a bit like auctions that offer a certificate of authenticity signed by the seller. And ultimately, it doesn't matter. I'm cool with people letting others know about a cool bit of gear whether they or someone else is selling it. A brief single plug is different from the untargetted spam that gets up everyone's nose.
Well said Chris.
 
Regards,
Tony
18/11/2011 10:37:29
Posted by ady on 16/11/2011 11:22:24:
I'm just stimulating and encouraging some technical conversation bogs
Yeah right.
 
Regards,
Tony
Thread: Have you recently submitted an article?
01/11/2011 17:47:45
Posted by Diane Carney on 31/10/2011 20:53:21:
To let you understand, David Clark is suffering intermittent bouts of quite severe illness.

My best wishes to David.
 
Regards,
Tony
31/10/2011 15:43:31
Diane -
 
I have an article I am working on which I hope to finish in the next few weeks - I usually send them direct to David - has that changed?
 
Regards,
Tony
Thread: New Viewer for MEW
03/07/2011 12:20:38
Posted by Tony Jeffree on 03/07/2011 11:41:27:
Posted by John Stevenson on 02/07/2011 17:05:36:
Some observations.
 
This on a brand new W7 machine with all the latest drivers.
 
Firefox 5 crashes with an flash error every time when trying to do a pdf print of all pages.
 
Explorer 9.0 works OK and saves the pdf at 12 meg, quality is readable but not as good as on screen.
 
The quality difference is between the screen viewer and how it saves so that looks as if it's down to computer settings.
 
John S.
 
 
Same issues with Firefox; IE9 couldn't even launch the viewer on my system, so something odd going on. Finally managed to get it working and printing on Google Chrome, uzing Bullzip PDF writer, but took ages and the final file size was about 57 megs. Will try it again using Chrome/Adobe Acrobat to see if it is any better.
Regards,
Tony
Actually it was Opera rather than Chrome...
 
Just tried again using Opera/Adobe PDF writer and produced a 22Meg file of indistibguishable quality from the larger one. It was also noticeably quicker this time.
 
Regards,
Tony
03/07/2011 11:50:34
Posted by blowlamp on 03/07/2011 11:42:16:
Could it be that the Adobe Flash thingy needs updating on some systems?
I know it doesn't work correctly on 64 bit systems though.
 
Martin.
My Adobe Flash is up to date, so I don't think it is that in my case - also, am using the 32-bit version of IE.
 
Regards,
Tony
03/07/2011 11:43:22
Posted by John Stevenson on 03/07/2011 10:38:47:

 
So why not cut the crap out and just put links up to the pdf files ?
 

John S.
Sounds like sense to me.
 
Regards,
Tony
03/07/2011 11:41:27
Posted by John Stevenson on 02/07/2011 17:05:36:
Some observations.
 
This on a brand new W7 machine with all the latest drivers.
 
Firefox 5 crashes with an flash error every time when trying to do a pdf print of all pages.
 
Explorer 9.0 works OK and saves the pdf at 12 meg, quality is readable but not as good as on screen.
 
The quality difference is between the screen viewer and how it saves so that looks as if it's down to computer settings.
 
John S.
 
 
Same issues with Firefox; IE9 couldn't even launch the viewer on my system, so something odd going on. Finally managed to get it working and printing on Google Chrome, uzing Bullzip PDF writer, but took ages and the final file size was about 57 megs. Will try it again using Chrome/Adobe Acrobat to see if it is any better.
Regards,
Tony
03/07/2011 11:39:18
Posted by David Clark 1 on 02/07/2011 18:44:42:
Hi Coal burner
Yes, all the old editions will be changed but it will take time.
regards David
 
That's great - thanks.
 
Regards,
Tony
Thread: I need a mill ? Manual or CNC??
01/07/2011 13:47:39
Posted by blowlamp on 01/07/2011 13:26:17:
It's a good point Rod, but it's possible to do things differently with CNC and drilling can be a good example.
 
For instance, much of the time it's far easier and quicker to use an endmill for hole drilling. This can done by defining the hole as a pocket and letting the CAM system take care of all the maths.
 
So if you've got a plate with say 5, 6, 6.6 and 10.2mm holes in it, you can use a 4mm endmill/slotdril to cut them all without changing tools, with no worry about different length drills.
 
 
Martin
 
Of course, that doesn't work for deep drilling, because end mills tend to be pretty short, but apart from that, its a great way to go.
 
Regards,
Tony

Edited By Tony Jeffree on 01/07/2011 13:48:06

01/07/2011 12:59:46
Posted by EtheAv8r on 01/07/2011 09:38:36:

Is there any reason why a CNC mill cannot be used as an occasional CNC router for ply and carbon sheet? Surely they mill has more cabability than the router?
 
No reason other than suitable spindle speeds. My Taig mill is capable of reasonably high spindle speeds; it will actually do 15000 RPM but I think that is probably more than the design limit of its headstock bearings, so I keep it down a bit. However, the way that mill is constructed means that it is asy to swap out the existing head for another one, e.g., something like a Kress router spindle, which would make short work of ply & carbon sheet.
 
Regards,
Tony
01/07/2011 12:54:07
Posted by Roderick Jenkins on 01/07/2011 12:23:47:

Can I just emphasize the need for headroom in a milling machine. This is hardly an ambitious setup yet the table is at the bottom of its travel (it's a rising knee - no quill) and the 5.6mm jobber drill is hard against the inside of the 1/4" chuck. There is no chance with a 1/2" chuck. If I had to choose between a small CNC mill and a larger manual one I would go for the manual one (but I'd like the small CNC as well please).
 
Rod
 
Rod -
 
That is a good point - there have been a couple of times when I have had to improvise in order to get sufficient height. Happily, on my Taig CNC mill you can unbolt the Z ways & shift it up a few inches to get a bit of extra headroom; the rigidity suffers but a useful get-out if you are desperate.
 
The ideal; combination is a small CNC mill and a larger CNC mill IMHO

Regards,
Tony
30/06/2011 23:12:05
Posted by Versaboss on 30/06/2011 22:52:11:

John, does what I see above mean that one can make parts just with the wizards of Mach3 alone? For a complete part one can run one wizard after the other,; the difference (compared to the 'usual' way via CAD-CAM) is only that the operator has to be near the machine for every step?

If that's correct, then it seems that this would make life much easier for many among us.

Greetings, Hansrudolf

That is correct. As long as you stay within the capabilities of the wizards, Mach 3 is all the software that you need.
 
Regards,
Tony
Thread: Using the technology
29/06/2011 22:55:27
Posted by Steve Garnett on 29/06/2011 19:35:14:
You really are trying to lower the tone here, aren't you, Tony!
I try my best, Steve...
 
Regards,
Tony
29/06/2011 13:07:46
Posted by Steve Garnett on 28/06/2011 22:49:21:
Posted by John Stevenson on 28/06/2011 22:31:09:
Steve,
I think I know the answer.
 
From my records you have paid no rent this month to view my pictures.
Cough up or the boys will be round. <bg>
 
Oh, is that what it is? Rent??? Perhaps I'll just stick with rent-free Chrome!
 
And trying to send round Santa's Slaves won't do any good. I think you'll find that there's a Claus in their contracts that means they won't work south of the Thames (or is it the Watford Gap?)
 
But it was worth looking at the pictures - good demo of CAD/CAM value.
 

Edited By Steve Garnett on 28/06/2011 22:50:52

Yep - he's sending round the rent boys...
 
Regards,
Tony
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