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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: 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.

26/11/2019 01:42:08

I've got two lathes - one a bench top Austrian job, the other generic a Far Eastern 12x36. The Austrian lathe came with a Rohm 3-jaw chuck with a single set of jaws - it's only a matter of reversing them and remembering that jaw 1 becomes jaw 3 when putting it them in backwards to grip larger diameters. It works well enough. The other one came with two sets of jaws, which seems to be normal and also works well. Is there reason behind this?  Is one arrangement better than the other? Just wondering!

Robin.

Edited By Robin Graham on 26/11/2019 01:44:25

Thread: Lathe boring tool - top rake?
20/11/2019 13:21:42
Posted by Martin Kyte on 20/11/2019 11:38:23:
Posted by Robin Graham on 20/11/2019 00:52:37:

Thanks for replies. Looking at David's (impressive!) range of DIY boring tools, and taking Zan's advice that zero rake works OK I made a tool (from silver steel) with zero rake. My need was for a 12mm blind hole 15mm deep with a flat bottom - so it is pretty slender. But it worked!

I notice that my first cuts gave a slightly conical bore, with the narrow end towards the headstock. After taking numerous spring cuts I ended up with a parallel bore, but I don't understand this behaviour. How does the tool know where it is?

Robin

If there is not much clearence between the wall of the bore and the shank of the tool you get swarf build up which can 'spring' the tool in a little and reduce the cut. It will get worse the deeper the bore because there is more swarf about.

regards Martin

Thanks Martin - that makes sense. My insert tool holders have through coolant, I guess that's why I haven't noticed this phenomenon before. Should have thought of that - my one-track mind was too focused on tool geometry!

Robin

Thread: Today's 'Live Chat' with TalkTalk
20/11/2019 01:48:28

Just venting my spleen here. I've been looking for a new ISP - I've been paying TalkTalk about £45 pcm for ADSL (ridiculous I know) and was looking for better deals. Talk Talk have advertised a plan for 35Mb/s fibre and unlimited landline for £26.95. So I did the online live chat thing with them - my question was simple enough, if I take this deal will I retain my current email addresses and landline number, or will I be treated as a new customer. How long does it take to answer that? About an hour and a quarter it seems - not delays (the replies came reasonably quickly), just trying to sell me stuff, ignoring my question, enquiring about my pattern of internet usage &c &c. Then 'I have the ideal package for you Robin, £29.95'. But I see the same thing for £26.95 on your website I say. 'I can do that for you Robin as you are a valued customer' comes the reply. Wonderful! I'm a valued customer! Not like that price is on your website for all comers....

Spleen vented.

Robin

 

Edited By Robin Graham on 20/11/2019 02:03:24

Thread: Lathe boring tool - top rake?
20/11/2019 00:52:37

Thanks for replies. Looking at David's (impressive!) range of DIY boring tools, and taking Zan's advice that zero rake works OK I made a tool (from silver steel) with zero rake. My need was for a 12mm blind hole 15mm deep with a flat bottom - so it is pretty slender. But it worked!

I notice that my first cuts gave a slightly conical bore, with the narrow end towards the headstock. After taking numerous spring cuts I ended up with a parallel bore, but I don't understand this behaviour. How does the tool know where it is?

Robin

18/11/2019 22:52:57

I've always used carbide insert boring tools but haven't got one small enough for what I want to do now, so I want to grind one from HSS.

All my carbide tip holders set the tip with a negative top rake - I don't know why, but they work. Is this something specific to carbide inserts or does boring in general require a different top rake from external turning?

The tool I want to make will be used to bore mild steel.

Any advice will be appreciated, Robin.

Thread: Lathe chuck guards - how many folk use them?
12/11/2019 23:26:25

Thanks for further discussion - I'm still not convinced that leaving the key in the chuck is a hazard in my particular circumstances. By which I mean one man, one lathe and an established pattern of working. Obviously things are different in an environment where machines are shared.

I'm not going to the stake (or even A&E) in defence of that view though - I am retraining myself.

Robin.

Thread: Ultrasonic toothbrushes
12/11/2019 23:03:40

Thanks for that Michael - interesting stuff. Keen as I was I didn't do my 'rust removal with an ultrasonic toothbrush' experiment because on reflection I thought domestic disharmony might ensue. It turned out that dog had a rotten tooth which has now dropped out - whether by nature or with the assistance of ultrasound I don't know. The animal is now chomping happily and the toothbrush has become redundant - it'll find it's way to my workshop I expect. In due course.

Robin

Thread: Reaming - depth of cut
06/11/2019 00:41:37

Thanks . The job is for someone who asked me to make a custom machine hand wheel to fit on a 12mm spindle - I haven't the spindle in hand, so I have to work to spec. Not my fault if it doesn't fit! If I were doing it for myself I would bore the hole then turn the spindle to fit, but I don't have that option.

I have an 11.5mm drill so will try with that on some scrap before going on. I read on the Sandvik site that reamers need to 'work', but they don't give any numbers. They don't want to commit themselves - too many variables I suspect!

Robin

05/11/2019 01:02:37

I want to ream out a 12mm x 50mm deep through hole in EN1A to H7 tolerance. I have little experience with reaming and looking on the internet I've seen recommendations for initial drill size varying between 1-2 thou and 10-20 thou below finished diameter. So I'm confused!

My plan is to use a machine reamer mounted in the lathe tailstock.

Any advice?

Robin.

Thread: Lathe chuck guards - how many folk use them?
05/11/2019 00:41:45

Thanks for comments about leaving the chuck key in. For me personally I don't think I'm going to get bitten by this because the process of removing the key after tightening has become instinctive (where I put afterwards is another matter - definitely STM issues there!). I guess that it may be more problematic in an industrial environment. But I like to try and understand these things.

Robin

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