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Member postings for Robin Graham

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

Thread: Colour matching.
01/01/2020 23:43:25

I make things mostly for my own use, but occasionally take on 'beer token' jobs for others when I think I can learn something. The latest is a simple enough engineering project, but needs to be colour matched. I've never tried that (my stuff is either shiny or black) - so I'm wondering how people go about it.

All I have is a photograph, which isn't much to go on I know. But GIMP will give me RGB values. Would that be that enough to identify a RAL colour?

I suspect that I'm dipping my toe into deep water here, and might not want go further, but I'd be interested in any advice.

Robin.

Edited By Robin Graham on 01/01/2020 23:51:37

Thread: Making a miniature leaf spring.
31/12/2019 23:26:29

Thanks for further replies. I have a copy of the 'Tubal Cain' book somewhere but can't lay my hand on it the moment. My problem isn't so much to do with annealing, but initial hardening. It's not easy to get such small parts from the flame or furnace to the quench before they have cooled too much. I think TC touches on this, but doesn't give advice beyond 'you've got to be quick'. That's from possibly faulty recollection though. I do remember his discussion of the 'blazing off' method for annealing though, now I'm reminded - thanks John.

I wondered if horologists (who presumably do this kind of thing routinely) had some cunning method for initial hardening unknown to TC....

I've made some experiments with hacksaw blades, they're a bit too thick for what I want, but I'm getting there.

Thanks for advice, Robin.

28/12/2019 23:26:32

Thanks for suggestions. I had thought of clockwork, but not having anything suitable from which I could scavenge a bit of spring I discounted the idea. However following MichaelG's mention of clock spring material I Googled and found Meadows & Passmore . Good Lord, they've got everything!

I like the suggestions for 'repurposing' blades from retractable rules and knackered junior hacksaws.I tried with the latter, but unsurprisingly it snapped before I could bend it tight enough. Which leads to my next question...

Meadows and Passmore supply the right stuff in annealed form, which they say has to be heat treated after forming, but they don't give details. Likewise I would have to anneal the hacksaw blade to form it, then re-harden. How does one go about that with such thin material? In my experiment with shim steel I heated the metal over the gas hob in the kitchen then chucked some water over it which simultaneously cooled the metal and extinguished the flame. But there must be another way less annoying to the wife!

Thanks also for other scavenging suggestions which I shall bear in mind.

Robin.

27/12/2019 22:52:58

I want to make a small leaf spring for a catch of my own devising. It needs to be in the form of a U about 1/4" high with maybe 3/16 between the arms and around 1/8 'front to back'. None of those dimensions are set in stone - they're just to give an idea of scale.

I tried a bit of 10 thou shim steel, which seemed springy, but not springy enough. Sadly when I tried to stiffen further it by heating/quenching it ended up softer.

Maybe bits from defunct electrical sockets? Cheapo feeler gauges?

Any suggestions would be welcome.

Robin

Thread: Bandsaw woes.
21/12/2019 01:44:52
Posted by JasonB on 20/12/2019 07:07:58:

I think the vice is an integral part of the base casting. Though the blade is pulling in the cut so would do the same whatever angle the work were held at eg blade not inline with plane that the arm moves in.

You are right Jason. The vice is indeed integral with the base casting. I'm now pretty sure that there are several problems with this machine. I think the pics of a square in the vice show that the axis on which the arm swings is not parallel to the vice base. Maybe I could fix this by making a 'sub base' with an arrangement of fixing/jacking screws to allow adjustment. The blade pulling might also a be problem, but perhaps secondary. This is becoming a challenge! I'll get a better saw when finances are better, but I don't like chucking stuff without having a go at fixing it.

Postie delivered a package with the Zoro logo on it today - my wife confiscated it immediately. What can it be I wonder? Do they sell socks?

Merry Xmas, and thanks to all who have helped me out with advice and entertaining engineering chat over the years I've been on this forum.

Robin

19/12/2019 23:21:31

Thanks for replies.

Bill - (Cornish Jack) maybe you got the first one I bought from them and sent back! It was even worse on vertical alignment than the replacement, and as you know there is no provision for adjustment.

I'll fit a new blade and see if that helps. When I bought the machine I also ordered a small stock of replacement blades from Axminster. They are 1470mm x 1/2" 14tpi carbon steel - I think I might still have one left, However it may be better to fit a third party blade. My Record woodworking BS certainly works better with Tuffsaw blades than the Record offerings.

I'll go for bimetal with M42 teeth. Ian at Tuffsaws stocks these with various pitches - from what's been said here it seems 8/12 or 10/14 Vari-Tooth might be a reasonable choice.

Having said that there is a fundamental problem with the machine which I'll have to address at some point if I want to get it to cut true:

bs_squareness1.jpg

bs_squareness2.jpg

 

Apologies for it being sideways - I forgot that if I want things to come out the right way up on this forum I have to turn my camera 90 degrees.

Robin.

 

 

 

Edited By Robin Graham on 19/12/2019 23:22:25

Edited By JasonB on 20/12/2019 07:03:16

19/12/2019 01:48:17

Yes, solid - why is that relevant?

Robin.

19/12/2019 00:19:09

I may have posted about this before in a 'which bandsaw should I buy' context. A Femi would be nice, but it's not going to happen for a while. So I have to live with what I've got.

Here is a cut in 1.5" aluminium square:

axibandsawbadness.jpg

At this point the blade jumped off the wheels (I was hoping to get all the way though, hence the redundant 'top' reminder). So two problems, which I think are linked: (a) the cut is way out of square and (b) the blade jumps from the wheels. Probably relevant is that the cut starts smoothly, but the machine makes a clunking noise and the arm 'hops' a little in time with the clunk before the blade jumps the wheels. I've watched the weld and it isn't catching in the workpiece, it happens when the weld is somewhere inside the machine.

Here's a pic of the machine:

axibandsaw.jpg

and another with the arm set at an angle to make it clearer how the castings fit together:

axibandsaw2.jpg

Obviously there are many variables here. What I'm after is advice on systematic diagnosis of the problem(s). Everything is fixable with a lathe and a mill!

Robin.

 

Edited By Robin Graham on 19/12/2019 00:37:00

Thread: Silver steel - bizarre Zoro pricing.
15/12/2019 00:29:03
Posted by jimmy b on 14/12/2019 04:49:17:

Robin, 333mm is a pack of 5.

Some smaller sizes are for packs of 25.

Jim

Thanks - I just looked at the 'headline' prices and missed that embarrassed .

Robin.

13/12/2019 22:51:42

I was ordering a couple of things from Zoro, came just shy of the £20 break for free delivery so I thought I'd bung in a length of 6mm silver steel.

333mm £6.20, 1000mm £3.89, 2000mm £15.19 all inc VAT. Think I know which length I'll go for...

Similar anomalies for other diameters.

Just thought it was worth mention in case anyone else is looking for silver steel.

Robin.

Edited By Robin Graham on 13/12/2019 22:52:58

Thread: Lathe lighting
07/12/2019 02:07:16

Thanks for further replies. I'll get rid the light and fix something to the splash guard. I've got a couple or three IKEA Janso flexible neck lights, but the clip on versions are pretty much useless for this type of thing - they don't stay put, and I read in another place that current offerings have a shorter neck than the old ones. I'll look around.

I've been investigating the Noah situation and it seems that he had a Hardinge for the prop shaft and cut an exclusive deal with Lie-Nielsen for hand tools. I might be wrong of course.

Robin.

06/12/2019 01:03:02

OK, thanks, I'm convinced (I think). Because I'm self-taught with this lathery business I have a tendency to assume that if there's an area where I disagree with the machine it's likely that the machine (or her designer) is right and I'm wrong. That colours my perceptions. I should be more bold.

Did Noah have a lathe on the Ark ? If so I'd bet it was an ML7. Some rust, cosmetic damage only I seem to hear him say.

Robin.

Edited By Robin Graham on 06/12/2019 01:04:39

06/12/2019 00:24:02

Thanks Pete - that's one of the things I hadn't thought of. Can you elaborate on your reasons for thinking that it's not a good idea to have the light moving with the carriage? I've found it helpful, when it doesn't bump into anything... but I'm a tyro.

Robin.

Edited By Robin Graham on 06/12/2019 00:24:45

Edited By Robin Graham on 06/12/2019 00:25:27

05/12/2019 23:44:05

This is the light on my lathe, as supplied:

img_2161.jpg

It has a 24V halogen capsule bulb wired from the internal lathe electrics - I'm not sure if AC or DC, but I suspect the former.

It's convenient that it moves with the saddle, but sometimes it gets in the way. For example in the setup above I had to take a handle off the compound wheel to avoid hitting the knuckle on the light.

I have some ideas about how this arrangement might be improved, either by relocating the existing light or replacing it entirely, but I'd be interested know how others would approach the problem. Someone will come up with something I haven't thought of for sure!.

Robin.

 

 

 

 

Edited By Robin Graham on 05/12/2019 23:46:20

Thread: Tapping a nylon hole.
01/12/2019 00:09:04

Well, I found a bit of nylon bar drilled nominally 8mm I guess - ID is 8.108 (+/- something), OD is 26.160 (+/- 0.015). It has been in a pan of boiling water for an hour. I'll let it cool in the water overnight, remeasure tomorrow and report later, if still capable of speech after interrogation about the reason for a lump of plastic in the porridge pan.

Robin.

Thread: Extending an M16 thread.
30/11/2019 23:28:38

Thanks for replies - it seems this is doable, I shall practice on a bit of scrap.

Grindstone - thanks for the link. I'll follow that up.

The alternative of making the whole thing from anew from scratch is the most efficient way forward I'm sure, but I have to balance the customer's budget, expectations and ideas against what I can do for a few beer tokens. I don't mind doing stuff for next to nothing if it teaches me something, but don't I want to end up out of pocket.

Robin.

PS - a chap in my town, having had sight of my workshop, asked me to make a camera mount for him. No problem, I've got a 3" round aluminium offcut which would serve. Made it, got treated to a couple of pints, then 'thanks for that, it would have cost me £75 to buy'. Nowt rummer than folk.

R.

 

 

Edited By Robin Graham on 30/11/2019 23:38:58

29/11/2019 23:38:08

I've had a request the extend the length of an M16 thread on the end of an 18mm bar. I think I would struggle with an M16 die and anyway I haven't got one - I've always cut anything above M12 on the lathe.

On the occasions when I've 'screwed up' (ho ho) whilst cutting threads and lost registration of tool and thread, I've not had much luck getting them properly back in sync - so I'm doubtful of my ability to extend an existing thread by this method. Am I being unduly pessimistic? Is this a viable technique with a bit of practice?

Of course the existing thread may have a relief groove before the shoulder (I haven't yet got hold of the part) which would further complicate matters, but let's assume not for the purpose of discussion.

Robin

Thread: Tapping a nylon hole.
29/11/2019 22:15:05
Posted by Sam Stones on 26/11/2019 00:33:16:

...

Neil,

Perhaps the thread pitch will affected, but surely the hole will also increase in diameter at higher temperatures?

That worried me too! Imagine a nylon part having an internal thread with a perfectly fitting nylon screw in it. Boil them up, they both swell to the same extent, and still fit together perfectly. But your unswollen tap is now smaller than the nylon screw...

Robin.

Thread: Inside chuck jaws
27/11/2019 21:19:04

Thanks for the further info about your design Martin - I'm certainly going to make a set of jaws along your lines and have contacted Neil about the possibility of contributing an article ( with due attribution of course!) about the build.

Robin.

26/11/2019 23:33:59

Thanks for replies - should have said it is 100mm self centring. The tooth profile is as in JasonB's pic, and you definitely have to swop jaws 1 and 3 to get them to meet in the middle. The Rohm chuck is very accurate in both configurations, better than the the bigger (150mm) 3-jaw on the other machine, but that's probably down to one being Rohm and the other unbranded Far Eastern rather than the design of the jaws.

Anyhow, interesting comments and a great tip from Martin C re soft jaws. I've been having trouble sourcing soft jaws for the 150mm chuck, this may be the way for me to go.

Robin.

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