Union Jubilee Clutch.

[Retired]

Hi,

Because of the bad weather I've managed to spend time practicing using EMS CAD.

As a novice I can't praise this EMS CAD enough; it's only a short while ago I couldn't draw using CAD and I've been trying various CAD programs over the last 14 years failing miserably with each. As I become more proficient I keep finding EMS CAD is opening up to me. I've mentioned this CAD program a number of times but it's worth adding again and it comes with a delightful tutor named Aurora Nestle.

http://www.emachineshop.com/

My initial drawings were merely to put my clutch idea onto paper but I've now progressed into proper scaled drawings of the clutch which I'm now finding incredibly useful. I had roughly measured the SPA drive belt allowing me to produce the initial drawings but a couple of days ago I braved the freezing workshop to double check the belt size and to double check again I browsed the web obtaining SPA belt data. The belt cross section plays a very important part in this clutch design and with accurate belt dimensions I set about producing the scaled drawings.

The cast iron blank measures slightly over 75mm diameter by 100mm long so this imposes limits as to the finished clutch size. The initial belt bearing was 55mm outer diameter but with the correct belt dimensions this has now been reduced to 47mm and this bearing is available in 7mm width. The bearing I've ordered is "61807 2RS" 35 x 47x 7mm. The "RS" denotes Rubber sealed.

I drew the two main clutch components using a common centre line; with accurate belt and bearing sizes known I worked around these drawing both components on the same page. by using the cursor to draw a box around each component I selected "Group" I was truly amazed as I then found out I could move each component around as if it was a finished part of the clutch; 0.5mm was added to the increments box allowing the arrow keys to nudge the components and it was wonderful to be able to use the arrow key to slide the components together just as they would once the clutch is completed.

What a breakthrough this was for me because now I could fine tune measurements and print off a working drawing to turn the parts against. I could try the belt in full drive and idle positions knowing that everything will fit perfectly. The thrust bearing was also changed and is now "16003 2RS" 17 x 35 x 8mm. I have a number of 10mm wide bearings in stock but 2mm difference in width is a lot in engineering terms.

To give me a visual aid I also roughly drew the two main components in 3D because it's very easy to make a mistake using the lathe and remove metal where it is needed? I tried to add the "V" halves to the 3D drawings but the program doesn't yet support this and also adding the two circlip (snap ring) grooves is a problem but I might overcome this with more practice?

My humble drawings will bring a smile to CAD experts but at least I'm now making progress with CAD.

On paper this clutch is progressing very well but I'll only know if it will work in real time once I make and install it which is the big problem due to the bad weather; it's snowing as I type.

Kind regards, Col.

           

[AlanBeckett]

Col,

It's very pretty but where are the Dimensions?

Alan

[camallison]

Col,

It's very pretty but where are the Dimensions?

Alan

If you look closely at the top drawing Alan, scaling is there - now get your scale rule out!

I must say Col, I am really impressed - like you, I have had problems getting to grips with any CAD program. Short attention span is my problem.

Colin

[pwdrive]

Hi Col, another nutty idea, how's about modifying a small syncro cone/gear for de clutching?

Lawrence.

[Retired]

Hi,

Thanks Big Al, good question. At the moment I've been concentrating on producing a scaled drawing and I hope to add all the dimensions once I've made and tried the clutch knowing it to work just in case anyone else is contemplating making one of these; I don't want to lead anyone up the garden path without being absolutely sure all is correct on my part.

This is a big learning curve for me; not only dreaming up the clutch design but in using CAD to produce the scaled drawings; please stick with me as I make slow progress.

For my use I'll add the measurements in pencil once I print the drawings off to start work.

If this clutch does work then I'll make two more for my Myford lathes as I can use the same size.

I know you are up to speed Alan using CAD so the overall sizes of the two clutch halves are 75 x 44mm for the inner and 75 x 50mm for the outer the bearings are already quoted and the motor shaft diameter is 19mm so it should be easy for you to work from these?

If you intend to make a similar clutch to fit your boat anchor 3HP vintage Brook Motor then you will have to increase all dimensions accordingly.

I've just sent you an email Alan with a link to the drawing on EMS then you can kick it around a bit?

Kind regards, Col.

[AlanBeckett]

I trust young Colin that the 'scaling' comment was 'Tongue-in-Cheek'.
The reason that all (Mechanical) Drawing say 'Do not scale this Drawing' ie 'Don't run your Rule over it', is that Plots are inherently inacurate. Also, it may not have been drawn accurately, but the Dimensions will be. Also, you often need accuracy better than the thickness of the lines. Where are you going to measure? The edges? The sides?

Sorry Col, 3D View gives complaints about the Drawing.
Send it again please?

Alan

[camallison]

I trust young Colin that the 'scaling' comment was 'Tongue-in-Cheek'.
The reason that all (Mechanical) Drawing say 'Do not scale this Drawing' ie 'Don't run your Rule over it', is that Plots are inherently inacurate. Also, it may not have been drawn accurately, but the Dimensions will be. Also, you often need accuracy better than the thickness of the lines. Where are you going to measure? The edges? The sides?

Sorry Col, 3D View gives complaints about the Drawing.
Send it again please?

Alan

Yes, tongue firmly in cheek

I served my time partly as a draughtsman and that was the response we apprentices unwittingly gave to the head of the drawing office school. Your reply was the one we always received in return.

Colin

[Retired]

Hi,

C'mon Big Al I did say I would add dimensions later once I had made the clutch and tested it in post #65? Until I have a working clutch this is only an idea so far and it might not even work because I've never seen this tried before.

The drawing is only in 2D so it won't open in 3D but I've just sent you more details Alan via email together with the rough 3D drawings you can rotate in 3D.

When I stated a scaled drawing it is certainly better scaled than drawing using a pencil onto a piece of scrap paper and apart from the bearing sizes the other sizes are not critical and again I've already added the two bearing sizes?

All I need now is some warm weather to allow me into the garage to play on the lathe in comfort; perhaps I should move in with you Colin or Lawrence until this project is completed because it keeps snowing here?

Kind regards, Col.

[AlanBeckett]

Colin,

Once upon a time, many moons ago, our Dept. Draughtsman sent a Drawing to the Workshops. It was a little trolley to put a piece of gear on so that we could wheel it round. I was sent to get it a month or so later and was informed that it would be ready after lunch - so what's new. When I went to get it they handed over a miniature trolley with 4 huge Casters welded on. Of course it had been drawn half size but the Metal Basher - I can still remember his name - had simply run his rule over the Drawing. 'I thought the Casters were a bit big' he said.
They made another one and the original proved ideal for removing engines from Beetles.

Alan

[pwdrive]

"All I need now is some warm weather to allow me into the garage to play on the lathe in comfort; perhaps I should move in with you Colin or Lawrence until this project is completed because it keeps snowing here?"

Yep...no problem £100 quid a week in real money plus a 20% hassle factor deposit, vegies, religious types, supporters of HMG need not apply.

Lawrence.