Stuart ‘No.1’ : a beginners tale..

[GarryCParticipant @garryc]

Hi Jason

This is great. I don't see why I can't have a go at this – but I'm not quite getting my head around how it works. I've not used any kind of cutter in the chuck before, my head is making hard work of it for some reason… Can I ask two questions which may help..

1. How is an accurate cut put on?

2. I still haven't got around to getting a little grinder – i've not done anything before with tool steel, I imagine its a very hard material of course – would I be able to file a sharp cutting edge by hand on say 1/8 round tool steel or would I need the grinder?

My lathe unfortunately does not have individual feed rates to choose from. The feed rate drops at an automatic amount with decrease in rpm and vice versa. The slowest it will run is about 90 – 100rpm, the feed rate is very slow then… although I could time it of course..

This is all very much appreciated, to say the least – it would be great to make and use my first attempt at toolmaking on the engine..

Many thanks.

Cheers.

Allan

 

 

 

Edited By Allan. on 12/05/2014 20:13:22

[JasonBModerator @jasonb]

Basically you measure the dia of the bar, then measure how far the tool bit sticks out and a bit of maths will give the diameter, on larger bars you can incorporate a screw of known pitch to push the tool bit out. That is why the smaller of the bars has been turned smooth around the cutter so it can be measured.

Unless you want to muck up a file don't go rubbing it on hardened steel!!. So no you can't file it but a dremel would do it at a push if you have one or if you are used to using one an 115mm angle grinder with the bit held in the vice but thats a last resort. Linisher or belt sander would also be a possibility if you don't have a grinder.

Thats the same with most lathes, the feed rate is a distance per rev of the chuck. Some have several ratios others just the one, if it gives an OK finish on external turning it will be OK for boring.

J

[GarryCParticipant @garryc]

Thanks Jason. I've got it now I think!

I'll get a cheap grinder and have a go (been meaning to get one for a while). No room on my workbench for it but I remember a while back someone on here fixing to a wooden base and using a workmate to hold, so I'll have a try at that.. I have a selection of bar stock as well now…

Many thanks again..

Cheers.

Allan.

[GarryCParticipant @garryc]

I wasn't sure to post this up, but it is really all part of the engine build so here goes – apologies to the some that will likely not be interested…

Making the Between Centers' Boring Bar…

I didn't have a 3/8 inch bar (that would have been a perfect size for the bearings) – so I had to turn a larger bar down a bit… The Final Bar length will be 8.5 inches..

The bar turned to 9.5mm.

Centering the bar on the mill ready to drill the tool bit hole. I've ordered some 1/8" round tool steel.. Drilled the hole to 3.2mm. Don't have the tool steel yet to test fit – may have to open out a bit perhaps…

In case anyone is wondering about the paper – my V Blocks did not come as a pair…

Center Drilling first..

Tool Bit hole drilled to 3.2mm.

I had marked horizontally through the end diameter when drilling the tool bit hole to use to rotate 90 degrees to drill the grub screw hole..

1st time I had tried tapping on the mill – and it was great.. 2.5mm M3 Tapping Size.

Test fitting the M3 grub screw. The length had to be cut to fit…

The grub screw in and cut to a length that will not protrude outside of the OD when tightened on the tool steel..

The finished Between Centres Boring bar – waiting for the tool steel and grinder to turn up. (3MM drill bit through the tool hole to illustrate only..)

Found a grinder for £20 – don't know what it will be like – and £2 for some tool steel. Hoping now i will be able to grind a suitable cutting edge when it arrives. Its already been dispatched apparently..

Regards

Allan.

 

Edited By Allan. on 14/05/2014 16:10:46

[Nick_GParticipant @nick_g]

.

Got to hand it to you Allan,

Once you get an idea and a job to do you don't hang about now do you.?

Regards, Nick

[JasonBModerator @jasonb]

Nicely done, just be careful you don't catch that tool making bug

[GarryCParticipant @garryc]

Hi Nick and Jason

I don't want to tempt fate – but it sure will be a great feeling if it does a good job on the bearings!

Cheers.

Allan.

[Neil WyattModerator @neilwyatt]

Allan,

From experience I know that boring like that has one BIG gotcha. If there is any play, anywhere, the 'boring table' (cross slide) will move, as the force from the cutter revolves through a full circle. This means it will find and exploit the tiniest looseness in the slides. Saddle and cross slide need to be clamped up tight (if you don't have a locking arrangement fitted) or you will not get a round hole and instead be treated to the assembly jinking up and down.

Yes I have learned this the hard way.

Neil

[GarryCParticipant @garryc]

Hi Neil

Thanks for the warning – I don't have any locking mechanism on the lathe for that, but I'll have a look and see if I can clamp manually, and take very light cuts…

I would never have thought of that but now you've said I can see the possibilities…! Especially on a tiny lathe like mine..

Ta very much!

Cheers.

Allan.

[JasonBModerator @jasonb]

Allan you should have a cap screw that will lock the saddle to the bed, you don't actually want it locked for this job but nipping it up slightly will stop and up/down movement. Likewise on the tailstock side of the cross slide where the gib adjustment screws are there should be one without a locknut which you do want to tighten to stop forward /aft movement.

But light cuts and a sharp tool should reduce any tendancy to jump about. I have taken 0.100" interupted cuts on iron castings with the between ctrs bars and not had problems.

[GarryCParticipant @garryc]

Thanks Jason, that sounds good – I'll have a look for them.

When the Grinder arrives I'll post a pic of my sharpening efforts on the tool steel. The photo's you posted of your boring bars are good and clear for me to try and copy the cutting edge…

Cheers.

Allan..

[GarryCParticipant @garryc]

Thought I would quickly put up a photo of my new Grinder – its tiny! I was going to use it in my workmate but think I'll likely use it in the vice, seems to run nice and smooth – the little bolts I used for fixing clamp down the rubber cups that were fitted under the base (included) so no vibration at all . Don't know how much I will use it yet and it would only be for small things I'm sure. Great for £20 incl del. – and the tool steel's arrived and fits my boring bar perfectly..

Wont be fitting the 'eye' guards as I would never use without full face safety wear…

1/8" Tool Steel fits perfectly in the boring bar 3.2mm hole..

May not get the chance to try grinding the tool until tomorrow though..

Regards

Allan.

[Bob Brown 1Participant @bobbrown1]

You may want to change one of the wheels usually the coarse one to a Silicon Carbide "Green Grit" or a similar one for grinding TCT tooling.

Bob

[GarryCParticipant @garryc]

Hi Bob

Thanks for the advice, you've encouraged me to do a bit of reading up on this which was again useful. I've been thinking to try some HSS Lathe tools to see if I get a better finish than the replaceable tip tools I'm using now, so I'm sure I'll soon find it useful – and now I'll know to get the 'Green Grit' if the fitted wheel(s) prove not suitable or wear out quickly..

Looking forward to having a go with it..

Cheers

Allan.

[Boiler BriParticipant @boilerbri]

This is a good thread guys.

just one question so far.

how do you adjust the tool in the between centre boring bar?

Bri

[Bob Brown 1Participant @bobbrown1]

The finer of the two wheels should be fine for HSS or even carbon steel but I have not used the coarse one since I purchased my bench grinder 10+ years ago and I changed almost straight away. One thing you will need at some point is a grinding wheel dresser to keep the wheels in good condition. Some thing else you will need is a pot of water but that one is easy and free, do not forget when grinding tools little and often is the rule I follow. e.g. a little grinding and a dunk to cool the tool, TCT not so critical.

Bob

BTW: Grind only steel as non ferrous metals tend to clog the wheels.

[GaryMParticipant @garym]

Hi Allan,

I don't think you'll look back once you've started to grind your own tools. When I got my lathe I bought a set of the ubiquitous brazed tip carbide tools sold by our usual suppliers. I couldn't understand why I was getting such a poor finish even allowing for the fact that I was a beginner. Someone, probably on here, suggested grinding my own. I was a bit wary of the grindstone, viewing it a bit like an unexploded bomb in the workshop (someone else's phrase). Anyway, I had a go, and the first tool I ground gave a much better finish than the brazed tools. Since then I've made quite a few others. If you've got a stock of tool steel and a grinder you're never stuck for that special shape.

Gary

[GaryMParticipant @garym]

Posted by Bob Brown 1 on 16/05/2014 19:28:01:

……… Some thing else you will need is a pot of water but that one is easy and free, do not forget when grinding tools little and often is the rule I follow. e.g. a little grinding and a dunk to cool the tool, TCT not so critical.

Bob

Hi Bob,

I've done this since I started grinding my own tools but I'm sure I read recently that you shouldn't dip them in water as it causes small cracks in the tip. Can someone with more knowledge than me comment on this.

Gary

[Bob Brown 1Participant @bobbrown1]

Gary,

 

I think hair line cracks is more to do with the state of the grinding wheel and how hot you let the tool get rather than quenching the tool, needless to say it you let the colour run it's too hot.

If you dress the wheel you will find that the wheel "cuts" a lot better than one that has not seen a dresser for a long time. Dressing the wheel is not just to square it up, it is also to remove the top layer to give a wheel has nice sharp grit that will cut rather than rub and just generate heat.

Bob.

 

Edited By Bob Brown 1 on 16/05/2014 20:38:08

[GarryCParticipant @garryc]

Hi Bri.

Jason gave a good description a few posts back (this thread), I haven't tried it yet myself but I understand it to be a matter of pulling / pushing the tool out manually and measuring. When looking to buy one I found they were very pricey and (the ones I found) had a 'micrometer' type device included that fitted onto to the tool for these adjustments.. I see no problem with doing it 'manually' though, especially as it's cost nothing really to make and it may get me into starting with tool grinding..

Hi Bob

Thanks, that is such a useful post! As I said I did some reading on this – but only about different types of grinding wheels…

Hi Gary

That does sound very positive and really interested to hear of your experiences with better finishes. I've tried to read up a bit about tool angles / shapes etc a few times now but have to admit its not 'going in' yet… I'll get there though..

Cheers.

Allan.

[Gordon WParticipant @gordonw]

Just use one of the cheapo brazed -tip turning tools as a wheel dresser, it's about all they are good for.

[GaryMParticipant @garym]

Bob,

I'll carry on dunking then.

I had a go at dressing the coarse wheel a while back when I'd noticed it wasn't cutting as well as when new. I used a single point tool from Machine Mart like this **LINK** However, I think I've made a bit of a bugger of the wheel. It sounded easy, just pass the tool across the wheel but the practice was a bit different. I've been using the fine wheel while I come up with a plan for getting it right.

Allan,

This **LINK** might help.

Gary

[Nick_GParticipant @nick_g]

.

A friend of mine (pro engineer) the other week advised me that I would be far better off with HSS for most of the things 'I' was likely to be doing on a lathe. So I heeded his advise and bought a few HSS tools. – He was right and I am adding to my collection.

With this in mind when I was at Harrogate last week I noticed there were enough changeable tipped tools for sale to sink a battleship. But by comparison HSS tooling was quite thin on the ground.

Can anyone please explain the reason for this.?

Cheers, Nick

[GaryMParticipant @garym]

I don't know the answer Nick, but it might be because model engineers grind their own HSS tools and maybe industry don't use them.

Gary

[Bob Brown 1Participant @bobbrown1]

Gary,

I use a wheel dresser which I find easy to use and the little wheels easy and cheap to replace.

Nick,

I think it depends a bit on what you are machining, most common materials are fine with HSS tools but when you get to hard materials and even some high grade and stainless steels, TCT are far better. I find the TC inserts are cheap enough and it only takes a short time to change the tip or turn it to a new edge then again there are the brazed ones which can be sharpened.

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