Degree indicator disc for your lathe

[DAPPH]

Ive been looking for a reasonable degree indicator disc that I can put on/in the rear end of the head stock shaft so that after putting a slotted pointer that you read the indication through somewhere on the body of the lathe so I can actually mark off individual and half degrees at the chuck or face plate end. As well as make some sort of accurate jig for grinding lathe cutter tips & sharpening small drills correctly .


There were many websites where I could print off a paper disc and paste it on some hard board etc. but I found that the distances in between all the degree markings were not fully accurate as things changed ever so slightly as it comes off my printer .


Most of the discs I've seen were paper or expensive aluminium ones for car engine timing or motorcycle engine timing , mainly from the USA.

eBay item 400942905918 seems good , as it is in plastic & wipe clean

If it is OK I hope to make an even bigger disc out of aluminium at say a 10 " dia so that I can play at making some accurate cogs and make an indexing head .

 

[brightspark]

just use a large gear wheel and a bracket with a spring and pin to hold it indexing

 

[DAPPH]

You'll have to draw what you mean please, for I was thinking of having an adjustable clamp to lock things solid on a nice meaty spiggot that also holds the timing disc on the rear of the headstock shaft every time I want to copy the degree angle at the chuck/faceplate side .

 

[Digger6135]

Buy a rotary table, they hace a good accuracy and if you can mount a chuck on it with a spigot down the centre bore, you can do all sorts.

Digger6135

 

[DAPPH]

This is the sort of retaining device I'm thinking of.


Where is the challenge in buying one Digger , aside from the challenge of finding the dosh ??

 

[Digger6135]

Thats a workable solution, and would work, you will have the satisfaction of having made it yourself.

Digger6135

 

[gordon stephenson]

Using a 10" disc the 1* divisions would be 0.08726" apart.
I always used to work out angles and distance in your head as.
the measurement is for the sake of round figure is 0.0175" (17 and a half thou) per inch of distance from the axis point, If that makes sense to you,

 

[Pete.]

You can just buy a degree wheel as used for timing camshafts. Get a big one if you need half-degree resolution.

http://www.summitracing.com/int/search/part-type/degree-wheels

 

[Wedg1e]

When you say 'grinding lathe cutter tips' do you mean shaping and sharpening the usual HSS square-section tooling used on small lathes?
The dodge I used was to bolt a small wedge cut from a piece of angle steel onto the tool rest of a bench grinder, with the wedge carefully calculated () to give anything rested on it a 7 degree tilt relative to a radial line through the wheel. This was claimed on some website I read as being a do-all angle for toolbit sharpening - and it works! Far better than guessing it or trying to hold the bit steady free-hand.

I often use AutoCAD to print stuff like graduated scales, drilling templates etc.; tell ACAD to print at 1:1 on A3 or A4 and on a decent printer (with decent paper) it'll be so close that ink bleed will be more of an issue than the printed accuracy.

 

[Wedg1e]

Using a 10" disc the 1* divisions would be 0.08726" apart.

So about two and a quarter millimetres then?

 

[AndyStobbs]

This is the clamp set-up I have made for my lathe (never got around to finishing milling it)


Drill the pinch bolt holes, then bore it a couple of thou over the spindle size, then split the 'cap' off the block and hey presto, thread the holes in the block, open out the holes in the clamp.

My piece inside the spindle is just a top hat with an interferance fit, I did initially fancy an expanding wedge design, but much easier to go for a press fit, with a draw bar to pull it in, and a sleeve and draw bar to remove it.

I needed 20 increments and found a milling cutter with the correct number of teeth, so machined the brim of the top hat to have a 1" shoulder, M8 bolt and washer clamp the cutter to the top hat, and then do whatever you like for indexing it.

This is the exact system I used when cutting the test splines on my jetski driveshaft (in aluminium) for 18T (with a different cutter) and it came out perfect, so it is plenty accurate enough.

 

[CRB]

Basic idea, but a mandrel in the rear of the headstock with your pin and you can use as many different gears as you have.

 

[roofman]

Basic idea, but a mandrel in the rear of the headstock with your pin and you can use as many different gears as you have.

That idea is perfect...on the hunt for an old little scrap lathe and salvage the headstock off it me thinks

 

[brightspark]

thats what i said in post 2 ,using a gear wheel u cant get any more acurate than that whatever the decree u want

Basic idea, but a mandrel in the rear of the headstock with your pin and you can use as many different gears as you have.

 

[Gritineye]

I made a pretty accurate direct reading dial this way..you can draw any disc yourself with most of the trial CAD programs. the one I drew for this job is attached at the bottom, bigger is better much more accurate.
I have some pics of using a gear to index somewhere, will dig them out and post if of any interest.

 

[CRB]

I have a number of drawings which i can send if you wish. There are probably some free ones on the 'net too.

 

[DAPPH]

Hi Gordon ,
If you were making your own disc why not make the circumference a precise 360 mm which is almost an 8" dia disc or make it a multiple of that using an engineering standard of " pi " to ....say five places ?


Then it would be so easy to accurately make up something like a precision trammel to give easy precise distances for each degree to be marked on the perimeter edge of the disc
Using a trammel set to 2 mm and marking the disc right across with the cross slide would all but eliminate any inaccuracies .

I gathered from my enginering apprenticeship early 1966 to early 1969 (full time military engineering college ) that' s how the older tool makers made their brass degree indicating discs so that they could cut gears & cogs but they used 1/8 or 1/4 inches spaces instead .

 

[gordon stephenson]

Wedg1e, my engineering brain is pre-decimal.

 

[Pete.]

Hi Gordon ,
If you were making your own disc why not make the circumference a precise 360 mm which is almost an 8" dia disc or make it a multiple of that using an engineering standard of " pi " to ....say five places ?
Then it would be so easy to accurately make up something like a precision trammel to give easy precise distances for each degree to be marked on the perimeter edge of the disc

Ouch no that's not right. An 8" disc will have a circumference of 638mm (and change). More importantly, marking one degree at a time will introduce compound errors. Just 0.01mm out each mark and your last mark will be 3.6mm out of position. This is why dividing heads are so widely used.

Dividing or direct-indexing even from a paper print is the best option.

 

[DAPPH]

I made a pretty accurate direct reading dial this way..you can draw any disc yourself with most of the trial CAD programs. the one I drew for this job is attached at the bottom, bigger is better much more accurate.
I have some pics of using a gear to index somewhere, will dig them out and post if of any interest.

I just " Lurv " that Atlas with the QCGB Grit in the eye , unfortunately my 1943 ish Sphere ( Atlas 10 " throw clone adaptation ??? ) has a simple gear box for back , neutral & reverse ,worse still the casing is made from Bakelite so not much chance of a fixing from there. I want to also make bigger witness /dial rims like yours as my eyesight is not getting any better.

I can't see any engraved or etched numbers on the dials are they sill unmarked or have you made them recently ?

The card came today in the post .. a nice bright red printed one , pity that the centre hole had already been made as it was a tad off centre.. soon fixed it and cleaned up the perimeter for a better circular shape by using double sided tape and centralizing it as best as possible on the face plate then putting the face plate back on the spindle. Very very gently using a sharp center drill I moved the centre hole over nearly two mm and shaved the perimeter of the disc to a proper circle by taking off about 0.2 to 0.5 mm in three places having first inserted the free rotating centre point in the new center hole to stop it chattering & /or slipping .

Yes , please for the pictures of your use of the gear to index things.