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Member postings for Will Bells

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

Thread: Emco compact 5 cnc lathe with Welturn
02/12/2015 15:50:24

Hi Emgee - I'm guessing my breakout board does exactly the same thing as the Homann ones do. I'll try what I have first .... if it goes pop, I've only wasted £14 (cheap compared to one of the ballscrews I had to replace !!!!!)

02/12/2015 14:24:44

Hi Mike

First an erratum ..... should have been Homann not Hofmann and the boards are called "Digispeed"

Secondly about where the 0 to 10v comes from, the jist from my simple Mechanical Engineer's brain is as follows:

This breakout board takes signals from Mach3 and outputs them again (and inputs as well of course), but in a protected way. So if anything happens to the lathe electrics, ie it lets out smoke and I get a nasty damaging electric spike from it, it's not passed down to the PC. So it provides (opto) isolation for inputs and outputs.

It also modifies and isolates the spindle speed control signal from Mach3.

Mach3 can provide output to control a spindle, but (I believe) it uses a digital signal (PWM). The breakout board modifies this output from the parallel port to provide an old school analogue voltage that varies between 0 to 10v, which probably came about to emulate the potentiometer control in the first place ??

Anyway, this can be used to control VFDs (or all the ones I have come across at least) in a simple manner - not as accurate as PWM, perhaps, but for my needs perfectly practical.

And somehow I'm sure I can use it to replace the manual potentiometer, perhaps by changing the voltage to suit. I'll know shortly when the Emco runs again and I can do some measurements.

Feedback from the spindle speed can be fed back into Mach3 as well from the shaft encoder. The resolution of the original Emco disc was too fine for Mach3 and so I have made and fitted a coarser one (ie less holes per revolution). Don't know how good this will turn out to be and whether fluctuations in spindle speed can be handled quickly enough, but we'll see.

01/12/2015 13:56:32

Hi Mike

If I have understood the principle (feel free to jump in Emgee if I have not grasped this correctly), the speed control potentiometer varies the voltage to the (probably) wiper terminal (other configurations are available !!!!) that is basically a ratio of the maximum voltage across the other legs.

So in principle, what is needed is to apply a voltage to the terminals that received the variable voltage and the motor speed should vary as a ratio of that voltage. And a standard way of outputting speed control signal is to use 0 to 10v.

Apparently there are boards available (eg Hoffmann) that can provide the interface. I have not gone into any detail or measured anything yet, but I'm thinking if that is the correct principle, then I may be lucky - it might be possible to use the breakout board output, which is isolated, almost directly.

I will need to ask for a bit of help when I get that far, but I can see there is a possibility.

The on / off control, on the other hand is more straightforward as I will use the outputs on the breakout board to switch a relay in the same way that the original switch did and probably use that switch to provide an override.

01/12/2015 11:03:20

Hi Chris, will do

The costs so far, not including any replacement mechanical refurbishment bits & pieces (bearings etc).

£94 for two new steppers and drivers.

£14 for a breakout board.

3 limit / homing sensors already had, but say £4 each from China (but microswitches are much cheaper )

Old PC and monitor was free from the loft

Mach3 Demo version is free (but I will upgrade when all works)

Fusion 360 free (for us)

Plus few quid for new connectors etc.

I am re-using the original power supply and motor speed control, but have made a new shaft encoder disc to match Mach3's maximum resolution. Emgee was kind enough to advise how to control the original motor board from Mach3, which I will do but at a later date.

Of course it may all go wrong ......... in which case I will go quiet for a long time blush

30/11/2015 18:24:14

Hi Chris

Impressed that you even showed willing to try learn how to use it ..... I don't have the skill or frustration threshold to write more than a couple of lines of G code in that manner.

I acquired a rusty 5 few weeks ago and after a (very) short deliberation decided to convert it to work with an external PC under Mach3 and try to use Fusion to do the CAM bit.

I have refurbed and slightly modified the mechanicals now, and I've made a big pile of obsolete electrical boards in exchange for some nice shiny modern electronic bits. Will finish the wiring in one / two weeks then it's ready for it's first trials.

Getting exciting now smiley

Cheers - Peter

Thread: Build threads.
12/11/2015 14:07:35

At the risk of having to don the old tin hat sharpish, I'm much more likely to read about bees than a blow-by-blow account of making a specific model.

I have been a subscriber of either ME or MEW since late 70's (of course I was in nappies) and guess what; i have never made a model since my dad stopped helping me make Airfix aeroplanes at Christmas.

I like reading snippets about models. And emissions, and telescopes, and bodging .and bees ...... Especially bees.

Cheers - Will

Thread: What is the strongest way to bond styrene to polyethylene
11/11/2015 09:32:24

Hi John

I am watching this thread even closer now as I have never had any real success bonding PP with adhesives.

One method that you might think about is Hot Plate Welding which is widely used in production and bonds like the proverbial. It's used for PP and it's used for ABS and I know it can sometimes be used with dissimilar plastics, but I have no idea whether yours are compatible because if the PP is unfilled, the melt temps are quite different.

The principle is easy enough - two surfaces are pushed against a hot aluminium plate which melts both interface surfaces. The plate is removed and the two parts pushed together. Almost Instantly bonded.

Could be worth some playing around ?

Cheers - Will

Thread: What is the strongest way to bond styrene onto ABS?
09/11/2015 11:45:52

Hi John

There are special solvent type adhesives that bond styrene based plastics (and Michael is right, ABS is a styrene). These work by melting the parent material, so they are probably the best bond you will get.

Never tried it, but styrene modelling cement may work.

I have seen DIY glues made with Acetone and the parent ABS melted into it for one off jobs - could be worth a try ?

Cheers - Will

Thread: What did you do today (2015)
06/11/2015 22:50:49

Tonight I finished decorating the "master" bedroom.

But, whilst I was doing that, the last part from my recently acquired rusty Emco Compact 5 CNC lathe was being de-rusted by electrolysis. I tried (honestly I did, Neil) to get some of that super green de-rusting stuff that was featured in a recent MEW article, but it was out of stock at Frost. So, in desperation I tried the electrolysis method.

It is absolutely brilliant - I just hooked up a 24v power supply, a couple of steel plates for the negative, mixed some washing soda with water in a bucket and put the rusty part in the solution with a positive lead attached. Let it bubble for a few hours and voila, rust rubs off.

Very impressed.

The wife's also impressed with the wallpaper effort, so now settling down with a nice Merlot to consider my next task with the Emco refurb..

Cheers - Will

Thread: Which mill
31/10/2015 13:47:05

Hi Hywel

I think I paid something like £600 for mine 15 years ago. A typical price advertised in the classified might be around £1200 recently.

Real pity you cannot get to see it because it doesn't look bad in the photos. There's no close up of the bed, but what you can see looks good and, apart from the additions (electrics and coolant) looks pretty well untouched.

Guess the risk of not seeing vs the price is a personal call .......but if it stays at that price I make a bid just for spares wink

Cheers - Will

31/10/2015 10:32:50

Hi Hywel

I've owned and quite heavily used (for a home workshop) an ex schools AEW Viceroy / Denford / Horizon for probably 15 years now. I think Denford took AEW over at some point and so I'm never totally sure which name to use.

It's a Vertical mill version - I personally wouldn't entertain a horizontal only mill because they are simply nowhere near as versatile; you can do just about anything you'd want to do with a vertical head, including drilling of course.

I too have a penchant for British machine tools that probably owes more to nostalgia than logic - but I first bought a brand new gleaming Chinese mill, the type with a round column, which I kept for less than 2 years before selling and buying the Horizon.

I did strip the sliding parts, clean and adjust it when I first got it, but it's never missed a beat since. I have no intention of changing it yet and would happily buy another if it bit the dust.

It's reasonably well made and accurate for it's class, with a small footprint, just the right size for my workshop. It will take a good cut without complaining, but it's not an industrial mill by any means. The slide ways do not have any proper protection, which has always worried me - no bellows or even felt wipers. Still, to be fair, it doesn't seem to be wearing and it has done a lot of hours of work. One slight restriction is that the Y movement will stiffen slightly now if there is a big torque on the bed, for example if I have a heavy dividing head on the far right of the bed and I mill something on the far left. The width of the shears could have been a bit wider to overcome that, but hey, I only notice it when I'm being lazy.

One thing that caught me out though was the stupid trick of calling it a metric mill. Nope, it was an imperial mill with approximated metric dials, I kid you not. I can only think that they could get away with that for education use, because it didn't look as if anyone had replaced anything and all leadscrews were the same. I screwed up a couple of parts before realising that 25mm of dial movement was really moving the beds 25.4. Grrrrr. I quickly slapped a DRO on it.

Cheers Will

Thread: Clarkson Autolock vs ER collets
17/10/2015 02:10:27

I have one Autolock chuck and a few ER collet chucks with a 30int mount for my manual mill plus the Cnc uses ER. I have never, ever, had a problem with any of the ER chucks slipping (nor the Clarkson come to that).

Some of the ER collet chucks are second hand Swiss ones and some of the chucks and most of the collets are low cost Chinese ones and they are all pretty similar in terms of my expectation of performance. Nothing slips and I do not need to overtighten, just nip them up sharpish against the low gear of the mill. Non of the nuts are bearing jobbies, just plain.

The cnc uses small ER16 collets which I bought directly from China as they were one of uthe few that stated a low runout. Certainly when they were delivered they were reliably reading less than 5 microns TIR in the spindle. Pretty good for cheap collets.

The Clarkson is left with a specific cutter in it and used occasionally, but it's a chew to change the cutter compared to the ER chucks so it doesn't get used often. And they can't be used with plain shanks which limits choice of (cheap) cutters.

I personally wouldn't dream of buying another Clarkson in preference to ER. But we're all different !!!!

Cheers Will

Thread: Newbie with an old Boley lathe
12/10/2015 23:39:22

Hi Paul

Carrying on from Neil's suggestion, it's possible that the tailstock barrel has a lot of axial play.

As said above, brass loves to snatch and pull the drill into it. So if the tailstock barrel can allow the drill to move freely by a significant amount towards the work then I could imagine that it could grab and seize up.

Just a thought ....

Regards (and welcome) - Will

Thread: Spindle runout acceptable?
05/10/2015 13:48:49

Hi Paul

I would expect (and want) my Myford lathe spindle runout to be much better than that, but I guess whether that's acceptable or not depends on what you want to do with it. A chuck will run out more than that, so it would still be usable.

But, I doubt the error is in the bearings. Much more likely the original spindle or it's fit to the bearings.

Perhaps check the runout on the morse taper as a double check ? It's always possible someone did something funny to the spindle nose at some point and as a last resort you could always skim it in situ and machine a non-standard chuck fitting for any new backplate.

Cheers - Will

Thread: Power Hacksaw
24/09/2015 00:09:52

I put my blades in forward facing and then turn them when they wear (it's a big old Manchester saw).

Frankly I have no idea which is best - both ways work and I just let the saw run until it finishes.

Cheers - Will

Thread: Brush finish on Stainless Steel
15/09/2015 00:05:51

Thanks gents, appreciate the advice - I'll get some blocks and give it a go.

Cheers - Will

Thread: Rotary Table Centering
14/09/2015 23:58:16

Hi Nick

The most accurate way in my experience is to use a DTI, such as the Verdict type held in the spindle chuck and clock off the central bore.

Both my tables have parallel holes and some types have morse tapers but they are concentric and accurate.

I made an adjustable holder for the DTI for using in the chuck, but often the standard accessories can be used.

Cheers - Will

Thread: Power tapping
14/09/2015 20:08:41

Hi Gordon

I'm one of those idiots - I do nearly all my tapping using a power drill in low speed with a clutch, have done for years.

It works very well, but 12mm steel would mean that you would need to be very accurate with the drill angle. So personally I may do one or two carefully with the drill, but for any quantity I would use a tapping head in the drill press. One of those arms sold for tapping that keep the head parallel would work I guess.

But for what it's worth, I set the clutch to a low setting, just enough to not ratchet out, so if there's a problem it stops. I power out in reverse as well.

I always put oil or tapping fluid on the tap.

I try to put the work vertically in the vice so that I can brace my elbows or forearms on a bench or the front of the vice and I make sure that the tap is perpendicular by eye by looking down, then from the side then down again and go. Wherever possible I use the right hand side of my vice so that if it kicks it's supported and doesn't swing upwards towards teeth and I find that I can position my arms best that way.

Sounds complicated, but believe me it's fast and surprisingly accurate once you get the hang of it and obviously the trick is getting the alignment right especially with thick material.

Anything up to 5 or 6mm with an M6 should be straight forward. But there isn't much margin for error in 12mm steel !!!!

Cheers = Will

Thread: Brush finish on Stainless Steel
13/09/2015 09:13:49

Thanks for the answers guys - Mr Fury, can you get a good even aesthetic linear pattern with the blocks if care is taken ?

Cheers - Will

Thread: Machining Hard Materials
13/09/2015 09:10:16

Thanks for the detail Andrew - I will try that and I have a couple of dog eared carbide end mills. I made a couple of accurate lathe tools to cut some worms (near to 0.7 mod) recently and rough ground then finished on the quorn. I had to make them spot on. It did the job, but it took a long time to get them accurate on the quorn after my hand approximation. Pre-milling them would have been much better.

Cheers - Will

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