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 ?|
Have you seen this video from Tubalcain2 (MrPete222)?
|Thread: Myford Super 7 tailstock barrel key|
Does this help?...
|Thread: thread indicator|
Have you seen this one?
Leaving everything engaged and putting the lathe into reverse is foolproof and the only way of cutting metric threads on the ML7 imperial version.
Edited By Jon Gibbs on 07/05/2014 16:44:25
|Thread: Smaller parting blades in dedicated toolholder?|
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!
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.
Hahaha - Very good! Far too quick for me!
Thanks for the inspiration.
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.
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
|Thread: Machine plate grouting (most common method)|
Another way often used with wood lathes is to add a ballast box and fill with kiln dried sand - either bagged or not.
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
|Thread: Smaller parting blades in dedicated toolholder?|
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.
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.
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.
Edited By Jon Gibbs on 01/05/2014 08:47:23
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.
|Thread: Just aquired a Myford lathe?|
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.
|Thread: Myford ML7 Back Gear|
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.
|Thread: Fly Cutter Milling Speed?|
Thank you for the words of warning. OK, I'll take it steady and tighten everything down well.
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?
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.
|Thread: Used machine tools|
|Thread: Pigtail mop thread help|
Thanks Frank. Suggestions much appreciated.
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.
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