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Member postings for Jon Gibbs

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

Thread: How to machine a flywheel ?
19/05/2014 11:50:40

Have you seen this video from Tubalcain2 (MrPete222)?

**LINK**

Jon

Thread: Myford Super 7 tailstock barrel key
11/05/2014 17:41:58

Does this help?...

**LINK**

Jon

Thread: thread indicator
07/05/2014 16:39:50
Posted by Paul Tummers on 06/05/2014 23:22:02:

Any idea were to go to buy a Myford indacator for a Super 7 at reasonable costs?

I badly need one in good shape.

Have you seen this one?

**LINK**

Leaving everything engaged and putting the lathe into reverse is foolproof and the only way of cutting metric threads on the ML7 imperial version.

HTH

Jon

Edited By Jon Gibbs on 07/05/2014 16:44:25

Thread: Smaller parting blades in dedicated toolholder?
06/05/2014 10:48:43

Thanks for the postings. Just to be clear I now have a couple of options of parting blade - the original 5/32" blade and the smaller 3/32" blade...

...but until I read your posts I hadn't put two-and-two together and realized that by grinding the cutting edge in the way I had I'd made the cut narrower than the bottom of the blade - doooh! embarrassed

I will see what the damage is with a micrometer when I get chance.

My feeling is that the square shoulders of the notch are actually pretty sharp in practice and will result in a neutral rake angle cut good for a thou or two? After all I was able to part well past the hollow behind the cutting edge last night when parting 40mm stock without any noticeable binding problems but I guess time will tell.

Jon

02/05/2014 11:12:37
Posted by Ian Phillips on 02/05/2014 10:36:13:
If your nocturnal bolt was a metric size you could have used a 50.8 fly cutter and got the blade within 0.5mm of the face!

Hahaha - Very good! Far too quick for me! laugh

Thanks for the inspiration.

Jon

02/05/2014 10:25:37

Post Script.

I had one of those 3am bolts of inspiration and realised that with a 2" diameter fly-cutter in the spindle I could mill the packer close to flush in-situ in the holder with the smaller blade holding everything firm - which is just what I did.

It now stands a about 30 thou proud of the toolpost.

Thanks again

Jon

01/05/2014 20:38:15

Ok, well based on Ian's comments. Here is the Mark II...

Managed to get the blade flush with the face of the toolholder and upright although I haven't milled the face of the packer piece flush yet. TBH I didn't want to muck it up given that it fits so nicely.

I thought about the retaining screw but it just isn't needed really.

...and it works as well as could be expected.

Many thanks for the suggestions

Jon

Thread: Machine plate grouting (most common method)
01/05/2014 14:13:28

Another way often used with wood lathes is to add a ballast box and fill with kiln dried sand - either bagged or not.

**LINK**

It will also do a good job of damping vibrations and isn't as much work as casting concrete by any means.

Hope this helps

Jon

Thread: Smaller parting blades in dedicated toolholder?
01/05/2014 10:56:59

Ian,

Having thought about your comments some more... As the end of the blade gets ground/honed, I'll be needing to lower the tool in the holder rather than shimming the holder or tool up as in the front toolpost.

Is the idea of shimming, to start with the tool above the lathe bed on shims and then gradually reduce the shims as the tool gets rehoned and reground?

Have I made a fundamental error - I guess I could just regrind a new front on the parting blade.

Jon

01/05/2014 09:41:52

Thanks Ian, Your points are well taken.

I have to admit I just knocked this up using a bit of plate I had about and it should have been thicker and taller in hindsight as you so rightly say and bring the blade out towards the front of the holder for flush cutting. I think that sounds like a good Mark 2.

As it happens the step on the loose plate goes about half way down the back of the blade but I didn't want to go too thin on the step. This again is where a thicker plate would have helped. Anyway that's why I need the pins in order to restore the blade to vertical because the dovetail recess pushes the blade towards the back and the plate isn't there to stop it.

So a taller, thicker plate next time.

I must admit for grinding I used the tailstock live centre point to mark the centre line on the blade (sharpy marked) when it was mounted before I ground the blade and rake first time around. So, I haven't had to resort to shimming yet but I guess that's always an option - I have a couple sets of cheap dismantled feeler guages ready for that purpose.

Jon

01/05/2014 08:46:37

Thanks for the replies.

As an experiment I decided to try to create a fixture for a 3/32" parting blade from Arc I already had.

Milled a flat step onto the side of a piece of flat MS bar and filed a dovetail onto the top to fit top of the toolpost recess and a matching one to accept the top of the thinner parting blade. After test-fitting the blade for vertical I found I needed a spacer between the blade and the back of the toolpost recess. In the end I used a couple of headless pins - one from each side.

I was a bit worried about stability but a couple of test cuts went pretty well - I'll try it out and see how it goes.

Here are a couple of photos. The first shows the new and old parting blades.

The second shows the small MS spacer in-place.

Jon

Edited By Jon Gibbs on 01/05/2014 08:47:23

30/04/2014 14:29:13

I've just bought one of these for my ML7 and it works very well but the blade is very wide - 5/32". I hadn't really appreciated this when I ordered it. It's 24mm tall and 5/32" wide.

So for most small projects it seems to waste quite a lot of material IMHO.

Do I buy a second blade and grind the business end narrower to create a more frugal parting blade or is there a neat way to modify the holder to match smaller blades for small projects?

Any advice or suggestions gratefully received.

Thanks

Jon

Thread: Just aquired a Myford lathe?
28/04/2014 13:54:17
Posted by John Stevenson on 28/04/2014 13:47:01:

One thing not in the book but very necessary for many owners [ note I stated owners, not users ] if that they should be sited facing east and enough space left in front for the prayer mat.

LOLs - Is this to ask for divine inspiration when trying to decide what to make?

To pray when things start to go wrong?

or is it to worship the lathe itself?

In my case it's probably most helpful to the knees when searching in the swarf and muck beneath the lathe for that 4BA grub screw I just dropped.

Jon

Thread: Myford ML7 Back Gear
28/04/2014 09:05:33

I suspect Paul is right. Have you remembered to disengage the bull-gear.

Unless you already have a suitable key you need to grind down the short end of a standard allen key to get at that locking screw.

You will need to check the size. Mine's an old imperial ML7 from 1950 and I suspect that yours might have metric allen screws as I remember reading somewhere about them changing over near to the end of production.

HTH

Jon

Thread: Fly Cutter Milling Speed?
24/04/2014 15:03:58

Hi Norman,

Thank you for the words of warning. OK, I'll take it steady and tighten everything down well.

Thanks again

Jon

24/04/2014 12:59:29

Hi Mick,

Thanks very much for the guidance.

I am using my lathe (Myford ML7) with a vertical slide so it's perhaps not as beefy as a dedicated milling machine?

Thanks again

Jon

24/04/2014 08:49:47

Dear All,

This may be a bit of a dumb question but do I follow the conventional rules about milling cutter speeds for a single tooth HSS fly-cutter? - or can I push it a bit faster?

I've just made a 2" diameter flycutter with a 1/4" round HSS toolbit. For milling mild steel at say 60 feet per minute I reckon it's about 120 RPM. Does that sound right?

I suppose if I'm too fast my toolbit will just dull more quickly, which is no great shakes, but I'd prefer to get it right.

Any guidance gratefully received - Many thanks.

Jon

Thread: Used machine tools
17/04/2014 15:34:40

Also here...

**LINK**

HTH

Jon

Thread: Pigtail mop thread help
08/04/2014 07:48:31

Thanks Frank. Suggestions much appreciated.

Jon

07/04/2014 14:35:27

John,

Thanks very much. As you say the pigtail is not a precision taper/thread so a bit of movement will not be a disaster.

I will not use this for the Morse Taper.

Jon

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