Spin Indexer question?

[Seafood]

Hi All

recently got a spin indexer I realise roughly how to use it and how to split it into 360 degrees but I need to make a scale for my mill that's got 200 divisions 360 divided by 200 is 1.8 degrees, is this possible as I can't work it out...

 

[chipenter]

You need to make a new disk with 20 holes , will give you 200 and any no divided into it .

Jeff

 

[tornitore45]

You need to make a new disk with 20 holes , will give you 200 and any no divided into it .

How would that work?

The 10 holes on the fixwd sector are 9 or 11 degrees apart actind as a nonius to advance or receed in 1 degree increments.

How would that allow you to move 1.8 degree from any one of the 20 hole plate?
Each hole in the 20 hole plate is spaced 18 degree Nx10 +/- Mx11 will never be a multiple of 1.8 no matter how you chose the two integers M and N.

 

[MachineTom]

What you need is a dividing head, its joy comes from the gearset of 40:1. giving the ability to take a few holes, and make many. Unlike the indexer which takes many holes but can only due a few.

Your 200 division issue can not be directly solved with a indexer. A plate with 200 holes could be made BUT, the c/c distance of the hole wold be about .050" with a bit of material between the holes, you are left with a locating pin diameter of .030"

If you want I'd make you one. I would use a dividing head, My mill has a bolt circle program but its limited to 99 holes.

Another way would be to use the indexer at 9 degree increments, and make 40 lines on your part, after the 40th division, carefully measure between 2 lines on the work and split the distance between them by rotating the work, now run another 40 lines, and half again, after 4 halfing the work you are done.

 

[rhankey]

You could also do it on a rotary table by advancing 1.8deg for each hole. You can use Excel, or one of numerous programs floating around to give you the progressive degrees so you don't end up with any cumulative error.

 

[tornitore45]

MachineTom 4x40=160 he needs 200 divisions A rotary table can do the work but but Seafood has an indexer, and asked help to resolve his problem without buying a rotary table.
Let's try to help him
The smallest integer multiple of 1.8 is 9 so he can divide a plate into 360:9 = 40 divisions 9 degrees apart.
Now he needs divide the 9 degree angle into 5 equal angles of 1.8 degrees each.
5 spacesto require 4 division lines between each of the original 40.
If he can offset the 40 divisions plate 4 times 1.8* and scribe 40 lines each time he is done.
Here things start getting interesting
The arc of 1.8* and the tangent of 1.8* have 1 digit difference on the 4th significand digit.
Dividing the distance between lines rather than the arc could be acceptable.
The problem is that he may be making a dial not much bigger than 2" and the 9* lines are 0.157" apart and the 1.8* lines need to be spaced abut 0.031".
I suggest to rig up a radial bar to create a radius of 2" to 4" and use an indicator to move a corresponding longer distance.
The numbers quoted here are for a 2" dial only, if it is not 2" everithing scales.

 

[rhankey]

Actually Tornitore45, a 40:1 dividing head can do 200 divisions with a number of standard plate hole patterns, including: 15, 20, 70, 75 or 90.

 

[MCRIPPPer]

Actually Tornitore45, a 40:1 dividing head can do 200 divisions with a number of standard plate hole patterns, including: 15, 20, 70, 75 or 90.

because all those numbers are multiples of 5.


but seafood needs to try and use the tool he has.

 

[LSEW]

Seafood, you don't mention if you have a DRO on your mill. This is a great application for a DRO, Just set up the hole circle & drill.

maury
www.lonestarengineworks.com

 

[GailInNM]

Here is a way that will work for the purposes of making a dial. Unfortunately my desk computer is down because of nearby lightning stike so no drawings possible. Hope the text will makethings clear enough.

For illustration purposes the following set up is assumed but you can change it aroundas desired. The spindex is mounted with the spindle parallel to the xaxis on the mill. The y axis zero is the center line of the spindex. An engraving tool with a fairly narrow angle point is used in the mill. The numbers I am giving are for a 2 inch diameter dial. If yours is different then scale them to match, ie for a 2.5 inch diameter dial multiply by 1.25.

First , with the y axis set at 0 (part centerline), index around every 18 degrees and engrave a line. Next offset yhe y axis by 0.0314 and if you want to be a perfectionist increase the z axis depth of cut by 0.0005. Again index around every 18 degrees with the same settling as the first time. Offset the y axis in the opposite direction by the same amount, 0.0318, and go around again.

Repeat with the following offsets.
Y0 Z0 (what you did first)
Y0.0314 Z-0.0005 (what you just did)
Y0.0628 Z-0.0020
Y0.0943 Z-0.0044
Y0.1253 Z-0.0079
Y0.1564 Z-0.0123 (only one side necessary)

If your engraving tool has a not so shallow angle, say greater than 30 degrees included angle, you might want to just use the first 3 values in the chart and increment every 9 degrees instead of 18 degrees. Both are about the same amount of work, but if you are making every 10th line longer or deeper then it's easier to keep track of them doing 18 degree spacing.

Don't be intimidated by the 4 place decimals. That type of prision is not necessary. Justmy way of expressing things.

Gail in NM

 

[Seafood]

Thank you for all yours kind comments I am fairly new to engineering and to be honest a lot of your maths is baffling me I don't have a dividing head or a rotary table or DRO but I did make a disc for my indexer with 20 holes as suggested in a piece of laminate as a trial and although the holes appear and measure accurate when the gauge was scribed the increments weren't even as in pic. not sure why?

It seems it may be a little beyond me at the moment with my limited tooling! thanks all again though for trying to help...

Lee