Member postings for Peter Wood 5

John

The Cutwell prices are more realistic. Only problem is that they are straight shank and I have the quicklock? type of chuck which takes threaded cutters.

Jo

Stop being a tease! I like the approach you have used of chain drilling followed by sawing through and filing to shape. Seems infinitely less stressful than milling with a 1mm cutter. I am off to Ally Pally now and will be looking for some fine piercing saws and diamond files I can grind to size.

Peter

Jason

Gulp. I will need a new mortgage at those prices! Thanks anyway.

Peter

Gentlemen

Thank you for all your advice. I had previously made similar slots of 1/16'' width by chain drilling and then carefully milling with a 1/16'' slot drill. With a lot of patience a reasonable result could be obtained without breaking too many mills. However as Neil notes in his first sentence, going down to 3/64'' seems a step too far.

In addition I had not been able to find any mills under 1/16'' at my usual sources.

I like the idea of making a d-bit out of silver steel and so I will get some at Ally Pally tomorrow, along with a stock of 3/64 drills!! Then I will practice on some scrap. Having put a lot of effort into shaping the con rod I don't want to start experimenting on it.

The other problem I foresaw which you have identified was that of filing the slots to shape after drilling / milling. The tip of my precious Swiss files would just fit into a 1/16th slot but certainly not 3/64''. I never thought of grinding them down. to fit! I think I will have to invest in anew set also tomorrow.

Looking at Jasons pictures it occurred to me that i might modify the ends of the con rod forks to receive circular bearing shells. I dread making split bearings in which one half is square and the other round and at this size the problems would be even greater. I know it is not strictly correct but I am not planning to enter any competitions. These are just memento for the grand children.

Finally thanks for correcting the drawing Jeff. I will have to explore Solidworks. looks a useful tool.

Peter

I am currently building the above engine from Hemingway Kits, having completed a Stuart 10V, a Mount Cross Engine, A Vulcan Beam Engine and part completed a Sir William Pumping engine. This time I fear I may have bitten off more than I can chew.

I have now got to the stage of making the connecting rod and have no idea how to proceed. In particular the 3/64'' slots for the bearing strap cotter pins seem impossible.

Having followed the Stuart Victoria thread I wonder if I could crave some of the same advice.

Thanks

Peter

Steve

A great idea for setting an item parallel. I must make one. However I don't understand how you take a skim off the backstop. Don't the chuck jaws get in the way?

Sorry if I am missing the obvious and it is a daft question.

Peter

Les

I have still got a couple of stanchions to make so I will try your suggested tool shape.

Another weakness of the Chronos design is that it does not turn perfect spheres.

As the tool goes over tdc towards the chuck the cutting pressure increases as it begins to bite into the bar. This tends to force the tool away from the chuck back into the ball.

Perhaps Neil's approach is better at this size but I don't know how well a form tool would handle stainless steel.

Peter

Les

I reground the tool with just an angled flat on its end (top clearance) and relied on the angle of the tool holder for front clearance. It worked OK but I was not too happy with the quality of cut I got.

I am making railing stanchions ( to go around the platform of a beam engine) from 1/4'' stainless steel.

On looking at the tool after turning several ballends I noted that a flat had worn whnere there should have been front clearance.

I also found it extremely difficult to centre the ball on the pre drilled cross holes which will carry the rails. In the end I turned the ball ends and then drilled the holes.

I am somewhat disappointed in this design of tool and am considering the type shown by Nobby for future projects.

Peter

Les

Thanks for the prompt response.

In fact the tool came with an angle ground on the end which I now realise was the front clearance. Not realising that the tool holder was drilled at a slight angle I then ground a small angle on the tool shank which effectively gave more front clearance.

In fact I discovered the tool was at an angle yesterday and assumed that the holder had been badly made!! I have almost completed making a new one with the hole drilled concentric with the holder body .

I guess I can throw it away now.

Peter

I recently bought one of the horizontal type of ball turning attachments. It came with a short length of 5mm tool steel which did not appear to have been shaped.

Can anyone advise on how the cutting edge should be ground?

It seems to me that the tool geometry on this set up ie cutting on the top of the rotating work, is totally different to normal side cutting and therefore must need a different presentation of the cutting edge.

Harold

Thanks so much for your posting. At last I have a clear understanding of the correct way to use the grinding wheel.

I really should have gone back to your book and studied it more closely.

Furthermore the photos on your web site have now clarified how a cup wheel should be used.

Thanks again.

Peter

David L and David C.

Your two responses illustrate my dilemma. Excuse my paraphrasing but David L says don't use the side of the wheel, with a very good argument about the difficulty of dressing, as well as perceived safety. David C argues that in practice everyone does use the side of the wheel and that the risk is small.

In my working career I was, for a while, in charge of H&S at a dozen large bakeries making a well known brand of bread. I soon learnt that most accidents were down to operatives doing the wrong things for the right reasons. That is they wanted to keep the job going so they took short cuts. I guess the same pressure is on people in engineering factories. Now I am not a 'jobsworth' about H&S but the best way of assessing risk or danger is by multiplying likelihood of an event against the consequences. That is when I come unstuck on this issue, because I cannot gauge the likelihood of a wheel shattering.

However, end of rant. David C - how about an article in MEW on the different approaches to tool grinding ie disc wheel techniques, use of cup wheels, choice of wheels etc.

Regards

Peter

Thanks for all the advice. However I still have a question about grinding tools.

I have an HH toolrest mounted in front of the grinder. I use the HH work holders to present the tool to the grindstone, partly for accuracy, and partly to keep my fingers out of harms way. However this means that the side and top rakes have to be ground on the side of the wheel!! This goes against all the safety advice.

In my defence, all the photos in HH's book, Tool and Cutter Sharpening, show the side of the wheel being used.

Mounting the toolrest at the side of the wheel might solve the problem but I would still have to grind the front clearance on the side of the wheel.

What is the correct techniquer?

Peter

All

Like Wolfie, I have struggled when making my own HSS tools. I built the HH toolrest and fitted it to work on the rim of the finer wheel of a cheap two wheel grinder. The results have been very variable and as a result I usually resort to indexable tools.

This thread has contained some excellent advice and I am tempted to try again but I really need clarification on grindstones. Some have recommended cup wheels and others diamond wheels but I am far from clear on which and how to use them.

1. What grade of cup stone do I use. There is usually a confusing choice on the stands at exhibitions though they all seem to be white.

2. Where or how is the tool presented to the cup wheel.

3. Similar question for diamond wheels - ie is the cutting done on the side of the wheel in which case does it have to be mounted at the opposite end of the grinder.

4. Finally, and most importantly , what about safety ie can I simply replace one or other of the existing wheels.

Peter

Clive

Thanks for the info.

I have now discovered how to adjust the overload clutch. The knurled ring is threaded!

However the device seems to operate in the reverse of your description. That is, when the tap holder is pushed in towards the main body it engages 1:1 drive in both directions. When it is moved away from the body, as would happen when the drill lever pressure is released, the 3:1 gearing engages. I have not risked trying it on a power drive so these observations aRre jus from handling it.

Not shown on the photo, just behind the tap holder and in front of the gearbox is a black ring which has a tapped hole in it through which the tap holder drive shaft can be seen. Have you any idea what its function is, or if something is missing?

Thanks

Peter

Can anyone identify this chuck which I acquired with my Myford S7b.

The end rotates when pulled forward and is abviously intended to hold square shank tools such as reamers or taps. When pushed back towards the main body it seems to engage a 3:1 gearbox.The knurled part is engraved with numbers 1- 4, and there is a register arrow on the main body which does not align with the numbers, and cannot be moved.

Thanks .

Peter

Mike

I bought the metal from Folkestone Engineering who stock a wide range of small BMS bar stock in EN3B.

All

I found a new 6mm slot drill in my drawer and decided to have another go having chain drilled most of the slot. This time I ran at 600rpm with between 0.5 and 1mm cuts. Now I could 'feel' the tool cutting the metal and whilst I had to wind harder there was little sign of heating. Having cut the central slot I then widened each side to the 6.8 mm target.

Job done!

Thanks again for all the help.

Peter

The metal was sold as BMS EN3B. I had already milled some 1.6 mm slots for the cotter pins at top speed, about 2500. with no problem, albeit I took tiny cuts and advanced very slowly.

My mill is an Amadeal 25LV.

I cannot do anymore until I order some new mills but I will take the consensus advice and use a slower speed, 600 rpm. I also plan to remove most of the metal by chain drilling most of the slot.

Thanks for all the advice.

Peter

I took the speed from Tubal Cains Model Engineers Handbook. The table on page 5.14 recommends 1600 rpm for a 1/4" slot drill in BDMS.

Each cut was about 1mm deep.

I should have added that I was advancing the table quite slowly - about 40mm/min - as the walls of the slot are only 1.3mm thick and I wanted to avoid any distortion. ( I am trying to make the parallel motion hanger straps for a Vulcan beam engine).

I am trying to mill a series of 6.5 mm slots about 70mm long in a piece of 4.8 mm thick BMS bar and have already blunted two slot drills on the first ho;e.

I started at 1600 rpm with neat cutting oil but after blunting the first drill I reduced the speed a little.

What am I doing wrong?