Saturday, 12 February 2011

Making an Indexing system.

A lot of small lathes and even some bigger lathes do not have any indexing system.
This post is going to show you how I have made a simple and cheap indexing system.
This is not difficult and took me about an hour and a half.
They only thing I will say is you have to take the time and effort to do it accurately.If not you might as well not bother as an indexing system that is not precise is an absolute waste of time.
My first lathe never had an indexing system so I thought i would make my own but it was not as simple as I thought.
I tried using a protractor dividers set squares and all sorts but nothing was accurate enough.
This is when I thought of the system I am going to show you.

The most important thing to use is a 24 tooth circular saw blade.
24 tooth is perfect as it divisible and gives you a wide range of devisions.
The blade must be in good condition as accuracy is paramount.

The system is made of polycarb as this is strong and easy to drill and cut.
First secure the blade to the polycarb with double sided tape to stop any movement.
Then lay a steel ruler across the blade from the point of one tooth to the corresponding tooth on the other side.
You have to be absolutely precise with this.
                                                        Click on pics to make them bigger
Now scribe both sides with a craft knife .A pencil is not good enough for this.

Do this all the way around and then remove the blade and join all the lines up.
If you have done this properly all the lines will cross the dead centre as below.

Now scribe two circles the outer one is the diameter of the finished disk and the inner where you will drill your indexing holes.

Here I have rubbed black wax over the disk to make all the lines show up better.
Next check the spindle size so that you will drill the right sized hole .You only get one go at this if you get it wrong it will be very hard to put right.
The centre is now drilled out with a forsener bit.

That done we are ready to drill the indexing holes.
I have used a pointed wood bit as it is easier to get precise positioning.
I rest the point on the cross and then start the dill.I do this for every hole stopping between holes to re position to avoid mistakes.
As you can see from the next pic every hole is exactly where it should be.

Now we can cut the disk to the required size on the bandsaw and tidy up the edge on the sanding disk.

The disk is fitted on the spindle and the chuck holds it in place as below.
All that is left is to make some sort of lever to locate in the indexing holes.
This is a simple polycarb strip with a bolt glued in it and fixed to the lathe bed.

As you can see from this last pic the indexing arm is under tension so that when located in the disk it is firm.

I hope i have explained this well but if there is something you are not sure of please contact me.

6 comments:

  1. A very interesting and money saving bit of tooling.

    Surprised you have not gotten more comments on this one.

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  2. Hi Mark.
    I get lots of viewings but not many comments.
    A pity realy as it would be good to know if what i am doing is worthwhile.

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  3. George,
    I think its great that you are sharing your ideas with us, very useful.
    I have not commented before, one of the silent viewers.

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  4. Thank you Dave your comment is very much appreciated

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  5. I have been wondering how to get around the issue and you have provided a plain English version on how to achieve it without any confusiion.
    Thank you

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  6. If you have any problems Keith let me know

    ReplyDelete