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Member postings for Paul Relf-Davies

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

Thread: Multicore Cable
26/01/2016 15:40:50

Would something like this suit? Can be bought by the meter in various colours.

P.

Thread: Arc Euro Updating Website
26/01/2016 09:43:03

Looks fine on my Windows 7 PC with the latest Chrome & IE11 as well as in Chrome, on my Android phone.

IMHO, the ArcEuroTrade site has always been a breath of fresh air in the world of ME orientated online shops, which are, for the most part awful!

cheers

P.

Thread: Making a draw bar thread adapter
18/12/2015 16:51:31

So, I also emailed ArcEuroTrade about this as well as posting here & I have just had a phone call from them to explain the situation.

Apparently the thread in the collet holder is deliberately cut a very little loose, to facilitate unscrewing. The theory is that the holder is being held in the quill by the taper. The draw bar and hence the thread is only there to provide a little security. Indeed, they confirmed that an M10 bolt would also be a little slack in the thread. This seems to make a certain amount of sense... after all would you want to end up with the collet holder and the draw-bar as a single piece, due to a jammed thread...?

To be completely honest, the adapter, as it stands, seems to function exactly as intended. Also I have to say that the customer service I have received from them on this is exemplary.

Cheers & Merry Christmas!

Paul.

18/12/2015 13:39:11

Thanks both for you replies...

I didn't have a have any M10 studding to hand the other night when I made the adapter, but I think I should be able to lay my hands on an M10 bolt this weekend...(for some reason I have penlty of M8 & M12...but no M10)

Unfortunately, screw cutting a thread that isn't an option, at least not at the moment. My lathe has an imperial lead screw & I don't have the change gears to concoct a metric thread.

P.

18/12/2015 12:50:11

Hi All.

I've acquired a 2MT ER25 collet chuck and collet set (the one ArcEuroTrade sell - the one with the M10 draw bar thread: 050-110-25530) and have been making an adapter to use it with my DW Mk1 mill, which has an M8 draw bar.

I purchased an M10x1.5 die and made my adapter - M10 male to M8 female.

The problem is that the adapter screws very sloppily into the collet holder. If I screw a normal M10 nut onto the adapter, there is no slop, so I guess the thread has been formed ok.

I'm wondering if the draw bar thread in these collet holders is an 'odd' M10 thread pitch. Does anyone know?

cheers

Paul

Thread: A new british standard?
02/12/2015 19:24:23
Hmmmm...I can't help thinking the author started out with the words 'well within...' before being the victim of some rather incompetent editing further down the chain....

Or maybe I'll being too generous..!?

P.
Thread: Fuel tap leak
28/11/2015 14:59:48

Fuel tap for what? The only experience I have with these would be with the fuel tap on my BSA D1, which is a push-pull action to open/close the flow and uses a small cylinder of cork on the plunger as a seal. this can dry out over time and shrink/disintegrate, causing a leak.

I think replacement cork seals are available, but if not, I've heard of people 'whittleing' then from a wine cork. They drill a through hole the size of the plunger's inner spindle then carefully carve away the remaining cork until they et a good fut in the valve.

cheers

P.

Thread: Hi all, another Paul....
27/11/2015 10:35:10

I've posted a few times, so I thought I'd better introduce myself.

I'm not so much a model engineering enthusiast (though I'm sure I've a small steam engine in me waiting to be built...) as a small-scale engineering fan.

I'm in the process of building up a small home workshop, which I intend to use for the manufacture of small parts for my assorted cars (various air-cooled VW based vehicles), my bike (a '55 BSA Bantam D1 Rigid), as well as some photographic & astronomical tools & accessories.

I have acquired an (as yet unidentified) Corbett's 3 3/4" lathe (It doesn't quite match anything on the Corbett's pages on Lathes.co.uk) and a DW Mk1 mill.

My plan is to buy the minimum of tooling to get me started, then to make additional engineering tools as I go...a knurling fixture or a ball cutter, for example.

I've made a few small items on the lathe, but my first 'proper' project is to adapt an EQ1 (ie very small) equatorial telescope mount to function as a long-duration astronomical camera tracker. In essence, I will need to turn up a new spindle threaded M10 on one end and 1/4"-20 on the other and an appropriately designed collar/spacer to mount on the spindle.

To be honest, I'm not anticipating any major challenges here, but it will be a good place to start....and the 1st of many projects.

cheers

Paul

Thread: New smaller Raspberry being given free with mag.
27/11/2015 09:59:10
It's showing as out of stock.
Thread: micrometer restoration
22/11/2015 11:15:13
Posted by Gordon W on 22/11/2015 10:39:13:

I would not worry about the ratchet working, they are not essential and we were told not to use them. They are only for giving a consistent load at each setting, a bit of practice will do that.

Indeed...that was my general theory. It would certainly be nice to have it working, even if just for a sense of completion, but I won't let the lack of a functioning ratchet stop me from using it!

P.

22/11/2015 10:19:53
Hmmmm...would that be similar to the Moly grease I use to pack wheel bearings & CV joints?

P.
21/11/2015 16:22:50
Posted by Bandersnatch on 21/11/2015 15:39:34:
Posted by Paul Davies on 16/11/2015 10:55:13:

Are you referring to this: 1620 Tool and Instrument Oil ?

Sorry, Paul - must have missed this. Yes, that is the stuff.

No probs Thanks

21/11/2015 09:53:19

So..a bit or an update...

Regarding the original mic...having stripped and cleaned it as much as possible, I have a nice, freely moving instrument, which I have calibrated with the 1" gauge & mini wrenches (that were all still in the box). The ratchet still doesn't work, but at the moment, I'm regarding that as a 'nice to have'. I shall continue to treat it to penetrating oil and see how I get over time (thanks fro the assorted links/suggestions for suitable oils).

In anticipation of the original mic not being salvageable, I bought off eBay (for the price of a couple of pints) a second M&W #940 mic. This was in very good mechanical condition(working ratchet!), but a good 45 thou out of adjustment(!). The original mic came with a spare anvil (to allow conversion to a 0-1" mic), which I have used on this second mic, giving me a second 0-1" mic, but with a deeper throat to the frame.

At some point I'll but a set of calibration gauges, so I can properly calibrate the full set of mic.

cheers

Paul

Thread: 12v and 5v power supplies
20/11/2015 09:44:44

Les,

I wouldn't recommend trying to power an RPi with less than a 1A supply. 500mA is about the minimum, but I've found they can be a little unstable with anything less than 1A, and more if you intend to power other devices (via USB, onboard GPIO, etc) from the RPi.

Also, why the LCD controller? The RPi outputs an HDMI signal, so why not just use a portable (ie 12v) LCD TV, such as this? After a little digging (and translation - its French) it seems that one draws 1A (12W at 12v) (and can run of batteries).

>>

cheers

Paul

Thread: working out screwcutting gears.
18/11/2015 16:30:29

Hi all,

I've been working on a simple (web-based) program to calculate change gears for my own use...it is still a work in progress, but using it, with the OP's gear, it has come up with the following combinations:

It should be noted that my program is designed to expect an imperial lead screw pitch, but should handle the 'imperialification' of a metric pitch, so these figures used a pitch of 7.69TPI, as opposed to 3mm.

I make no guaranteed that these combination will actually fit together...I'm still working on that feature!

Simple:

A : D -> Result (Error)
60 : 63 -> 8.0745 TPI (0.9313% )

Compound:

A : B / C : D -> Result (Error)
50 : 48 / 36 : 39 -> 7.9976 TPI (0.0300%)
50 : 56 / 42 : 39 -> 7.9976 TPI (0.0300%)
50 : 39 / 36 : 48 -> 7.9976 TPI (0.0300%)
50 : 39 / 42 : 56 -> 7.9976 TPI (0.0300%)
56 : 63 / 40 : 37 -> 8.0024 TPI (0.0301%)
56 : 37 / 40 : 63 -> 8.0024 TPI (0.0301%)
60 : 54 / 32 : 37 -> 8.0024 TPI (0.0301%)
60 : 37 / 32 : 54 -> 8.0024 TPI (0.0301%)

(under the covers, the program is just working out the resulting TPI for a given lead screw and set of gears for all possible combinations, and then the result with the specified target (in this case 8TPI) and filtering out those where the error is too great.

The calculation used is as follows (using the 1st compound set as an example)

(Driven / Spindle) x (Leadscrew gear / Driver) x Leadscrew TPI

(B/A) x (D/C) x Leadscrew TPI

(48/50) x (39/36) x Leadscrew TPI

0.96 x 1.083 x 7.69

1.04 x 7.69

7.9976, which is 0.03% under the target of 8TPI

I hope this is of use....(and I'd be very grateful if anyone could point out any errors...I'm still 'enjoying' the gear-combination calculation learning curve!)

cheers

Paul

Thread: micrometer restoration
16/11/2015 10:55:13

Are you referring to this: 1620 Tool and Instrument Oil ?

 

Edited By Paul Davies on 16/11/2015 10:56:21

16/11/2015 10:40:34

Hi George,

I've tried that. The screw in the top is stuck fast. I don't want to force it and risk damaging the screw-driver slot.

That said, I did notice that I'd starting to get a tiny amount of movement in the ratchet, now that it has been treated to a good soaking in penetrating oil. I'm hopeful it will eventually free up, given enough time & oil.

cheers

Paul

16/11/2015 09:35:09

All little progress over the weekend...

With generous application of penetrating oil...time...and a little gentle persuasion, I have been able to get the thimble to fully unscrew from the spindle/thimble assembly. As such, I should now be able to get the full range of measurement out of the mic.

I've given the sleeve a good clean, but since the ratchet is still not working, I've set the thimble/ratchet assembly aside, full of penetrating oil, to give it more time to steep.

cheers

Paul

13/11/2015 22:41:21
I completely agree...I have no intension of forceing anything! I gave it a good drenching in penetrating oil this evening, which I will leave overnight. I'll keep at it over the next few days to try to flush it out. Gently does it...

Cheers

Paul
13/11/2015 20:05:55

Well,

Having got home and done a little more digging, I can confirm that the mic. is indeed a model 940, from the engraving on it and that the problem is a combination of the clamp wheel being tightly done up as well as the innards being all gummed up.

I've given it a generous dose of penetrating oil and have been able to slacken the clamp off and the thimble now turns freely out to .920", where it stops & is well & truly stuck. The ratchet also refuses to move.

I'll leave it to soak in over night, and see how it is in the morning.

BTW, I unscrewed the clamp completely and discovered, where the vernier section screws into the cast 'C' that there seems to be a lot of rust.

I suspect that despite the clean exterior, this mic may have been for a bath at some time in the past...

I may just bid on the other 940 on ebay...just to ensure I have a fully functional set., in case this one proves too far gone.

cheers

Paul.

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