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Compound needs a better degree dial

garageguy

Super User
Premium Member
How about the degree tape they use on crankshaft harmonic balancers. Hot rodders use them all the time. Just wrap it around your compound base. I'd like to see what you come up with because my lathe has a pitifully poor degree marking system.
 

Susquatch

Ultra Member
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Here's my last thought for the day: quick and dirty. Buy adhesive metal measuring tapes from Lee Valley 70539-adhesive-bench-tapes. if you buy the inch/metric scale tape and cut the tape in half lengthwise and then use the mm scale and wrap it around the base of the compound, total error error is about 1.1 degrees over 360 degrees or less because you already have part of the circle covered by your existing scale.

Sorry for being late to reply. Nephew's Wedding last night.

I must have had too much pop. I don't understand your last thought for the day. Perhaps that's because I was born and raised in an Imperial world. I can speak metric but I think in imperial.
 

Gordie

Active Member
Good morning.! You talked about favouring a graduated ring, to slip over your tool post, rather than disk between the post and compound. I thought that the metal tape applied directly to the tool post would do as well as a ring. I said compound which should have been wrap around the base of your tool post. Tape's annealed to make that easy. I went metric because you quoted a 115 mm D. Turns out when you do the math that the metric graduations work better though. $20 solution.
 

Susquatch

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Good morning.! You talked about favouring a graduated ring, to slip over your tool post, rather than disk between the post and compound. I thought that the metal tape applied directly to the tool post would do as well as a ring. I said compound which should have been wrap around the base of your tool post. Tape's annealed to make that easy. I went metric because you quoted a 115 mm D. Turns out when you do the math that the metric graduations work better though. $20 solution.

I guess I'm still not understanding. Except for the one very specific outside circumference of 360 mm, how do you translate mm of tape length to degrees without math?
 

Gordie

Active Member
Last try, then I'll assume that I'm missing something. 1 mm = roughly 1 degree if your tool post is 115mm D. 115mmx Pi(D) = circumference of 361.1, an error of .003/division. Once installed, you can reference from your existing graduations. Write major divisions on the tape, if you want. No math, just counting graduations.
 
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kstrauss

Well-Known Member
These aren't AliEx priced but they may also give more flexibility in mounting and certainly would have better tech support:

AksIM™ Off-Axis Rotary Absolute Magnetic Encoder Module

The sparkies (said with respect....) gave me one of this family to build into a high end slip ring assembly I worked on in a past life. I'll refer you to the data sheet for the important details but I can somehow imagine feeding the output into a TouchDRO......

D :cool:
They look expensive! What is the approximate price?
 

Bandit

Ultra Member
What Gordie is trying to say is if the dia. of the compound base is 115mm, that times by Pi ( 3.14) is equal to 361.1mm in circumference. Being as there is 360 degrees in a circle, this is just slightly more then 1 mm (1.003) equaling 1 degree of of a circle. By my eye I can't see the difference between 1.00mm or 1.003mm. (But then I was legally blind until just a few years ago).
So if one were to put a tape around the compound base, glue, pin, etc., every mm. would mean 1+.003 degree of rotation. Quick and dirty, close enough for a lot of work.
I think I need to take a look at my lathe compound bases, and try this. Now just need to set up the dummy hands so I can count more then 10, not haveing to take my boots off. (It doesn't have boots, good for 20 there).
 

Susquatch

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Lst try, then I'll assume that I'm missing something. 1 mm = roughly 1 degree if your tool post is 115mm D. 115mmx Pi(D) = circumference of 361.1, an error of .003/division. Once installed, you can reference from your existing graduations. Write major divisions on the tape, if you want. No math, just counting graduations.

Last shot is usually the ringer.

Now I believe I understand what you are suggesting and why. Pretty big coincidence if you ask me!

@Bandit confirms my understanding.

Kinda cool that you noticed that!

I guess I was blind to your discovery cuz I would never have suspected such a coincidence.

But........

First, I could never accept the 361.1 because the error accumulates at either end. And even though I said I'm just looking for quick and dirty, I still have a pretty tight standard for what that might mean. Prolly within a 3rd of a degree???

Second, the 115 was only a rough number (in fact, I'm not even sure I remember it correctly) for the OD of the bottom of the compound. It could be significantly more or less.

I suppose I could make the base either bigger with a shim layer or smaller by turning it on the lathe a bit such that the result is exactly 360mm.

But as simple as that may be, it's still not like a ring marked in degrees with bold numbers at every 15 degrees, even bolder at 30, and still bolder yet every 90. In my opinion, that is how all lathe compounds should be marked. I'm just trying to get closer to that rather arbitrary minimum standard.
 

Tecnico

(Dave)
Premium Member
They look expensive! What is the approximate price?

I'm afraid I don't have that info, best I can say is no doubt more then Aliex. ;)

I noticed they have some even more interesting models, scroll down & see the rings on this page. I wonder if there are some that would slide over the existing compound ring.

D :cool:
 

Dabbler

ersatz engineer
it's still not like a ring marked in degrees with bold numbers at every 15 degrees, even bolder at 30, and still bolder yet every 90. In my opinion, that is how all lathe compounds should be marked.
I've been thinking about this since the first post...

One the spring rush is over and you get to the straw-in-mouth and rocking-in-the-chair summer farmer phase ;), You might consider mounting the compound on your rotary table and just marking out the divisions you need all the way around... If your mill and lathe aren't in daily use, it could be spread over several days, to mitigate the tedium.

just a thought...
 

Susquatch

Ultra Member
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Premium Member
Good fortune in your journey Pilgrim.

Good way to put it. Sometimes I feel exactly like that.

Still rather amazed at your observation of how close the size is to a metric ruler. Kudos to you for noticing that!

Of interest, the exact diameter for the ruler itself is 114.59. So if I assume my 115 was correct, a very slight removal of material on the lathe would get me there. If my pilgrimage flounders, I may end up there yet! If so, I would probably use a marker or something similar to identify the 15/30/60 degree intervals.
 

Susquatch

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If your mill and lathe aren't in daily use, it could be spread over several days, to mitigate the tedium.

Although I am capable of such tedium, it wouldn't be something I would ever look forward to. It's right up there with removing the sand from my 1/2km long driveway using a pair of tweezers.

The hard part for me would be the numbers.
 

historicalarms

Ultra Member
With all the "tedium" involved in the electronics part of this thread ...I can see a job opportunity for some healthy person making etched plates for everyone of us that has a crude "Taiwanese's" scale on their import lathe....after all. there are guys that can etch/mark scope turrets' that can reliably & repeatably hit small targets at atrocious ranges . an adapto plate for a lathe should be child's play.
 

Tom O

Ultra Member
There is plans for this type of scribe marker in one of my books for this purpose its lever action and counts off the scribes even giving the longer ten division. I’m thinking maybe in the book on making homemade gear cutters I’ll take a look.
 

Susquatch

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With all the "tedium" involved in the electronics part of this thread ...I can see a job opportunity for some healthy person making etched plates for everyone of us that has a crude "Taiwanese's" scale on their import lathe....after all. there are guys that can etch/mark scope turrets' that can reliably & repeatably hit small targets at atrocious ranges . an adapto plate for a lathe should be child's play.

I agree. I have seen lots of lathes like mine. It's a common oversight to put a crappy angle index on there that only does a third or less of the rotation.

I was half expecting someone to chime in with a link to some small outfit that churns out custom dials for this very application at a decent price.
 
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