Thread: Co-axial indicators

Hi Simon,
You could use a centre finder or even a wriggler.
I have with great repeatability.
I will give you more details when I get inside unless someone beats me to it.

Phil

Simon,
I bought a cheap one (around US$50) and have used it a few times.
The sample I received has been fine for non-critical work. Compared with a Mitutoyo DTI it did not show a marked difference in a single comparison (hole alignment for vertical milling). I have only used it in the vertical orientation, and sense that it would not be reliable in the horizontal orientation with a long tip. Certainly a major plus compared with a DTI is that you do not have to follow the dial as you rotate the spindle.

Re brand name I personally don't take that to mean anything, except for known reliable brands.
A few points:
The scale graduations don't mean much unless the tip length and angle happen to correspond with the scale calibration.
This style of centering indicator is supposedly capable of use with the spindle running - at up to 800 rpm (!) - but I am not that adventurous.
The accuracy would seem to be sensitive to odd bits of stuff that stick to the rubbing surface, and possibly also to wear in short order, esp if you regularly operate it with the spindle running. I decided not to lubricate the rubbing surface because lubrication would probably just attract dirt to the critical rubbing face.

Given the choice now I would go for the M&W ball joint mount you found.
But I will keep the centering indicator to save wear and tear on my neck joints.

Cheers,
Bill

I assume one of your indicators is a dial test / finger style? If not you need one of those, you will get a lot more use out of it than a knock off Co-ax.

Get yourself one of these half round indicator holders. http://www.machineryhouse.com.au/Q437

I have an original Mitutoyo one, but I needed two identical ones for a job last year. I bought two of the H & F ones, They work just as well as the Mits.

I got a quote on a new Mits $245 bucks.

Regards Phil.

Hi guys,

Thanks for your replies and help.

Hi Bill, I had noticed they claim to be good to 500 rpm (or it may be 800) but the first thing I thought of was why would you need to spin the spindle that fast? A jog speed of 20 rpm would be more than enough. WRT accuracy, I'm not interested. I'm more wanting to use it as a comparator rather than for actual measurement which is what I assume they are designed for and so repeatability is the key. Never thought to use it in the horizontal plane. I concur that it would have to suffer with droop, especially with the longer arms.

Hi Phil (Machtool) Thanks for the advice. Yes I meant a dial test indicator. Excuse my ignorance as a self taught hack I get dial and dial test confused from time to time! I remember when you bought that thing now that you mention it. I think you referred to it as a gooseneck? I had no idea why anyone would need one of those and now I know! I think you may have saved me $100 and much frustration! I think that will fit the bill nicely. Thanks!

Hi Phil (steamwhisperer) you still out there? I (think) I understand the concept of using the edge finder. I have used it to find the centre of a dowel pin or shaft but not a hole. Assume the same but opposite? When you have it dead centre in say the X axis, any movement of the Y in either direction will deflect it off, then do same for Y axis?

Machtool, did you say $245 for a mits gooseneck or co-axial indicator?

Cheers,

Simon

Originally Posted by simonl

Machtool, did you say $245 for a mits gooseneck or co-axial indicator?

I only got a quote on the Mits gooseneck. At $245, too rich for my blood. The one I have, I must have had that for 30 years now. His name is Gunther, after the guy I bought it off. I was on a job in Braeside, so I just drove out to H&F. I actually bought 4 of them at $22 each, 2 for me, and two for a mate. And at that money, they work better than I expected.

Not sure Mits even make a Co-ax, but if they did it would be expensive.

Regards Phil.

(On edit). Just did a crawl of Ebay to see what they had. Found a beautiful Noga, that will do the same as a gooseneck. Its an extra $40 bucks also, but nice looking.

http://www.ebay.com.au/itm/NOGA-NF10.../111327518785?

Originally Posted by Machtool

Just did a crawl of Ebay to see what they had. Found a beautiful Noga, that will do the same as a gooseneck. Its an extra $40 bucks also, but nice looking.

http://www.ebay.com.au/itm/NOGA-NF10.../111327518785?

You turned up more than I found. $60 is probably justified but $30 for delivery (for such a small item) is a bit rich!

I've ordered both a M&W holder and the Hairy forbes holder. They should do me nicely.

Simon

I find my h&f holder next to useless for sweeping smaller bores. The clamp that holds the dti is not in line with the spigot, so the stylus ends up off center by about 5mm. It would be better if I put the dti on a small round mount first and put that in the clamp, but the V's that clamp the bar are not the same size so it sits at an angle. I'm sure I could fix it but I have never bothered.

Ew

Originally Posted by Ueee

I find my h&f holder next to useless for sweeping smaller bores. The clamp that holds the dti is not in line with the spigot, so the stylus ends up off center by about 5mm. It would be better if I put the dti on a small round mount first and put that in the clamp, but the V's that clamp the bar are not the same size so it sits at an angle. I'm sure I could fix it but I have never bothered.

Ew

That seems to be the same problem I have ATM. Looking at the pic on H&F website, it does look like it's all in line, since both the post and the DTI holder are mounted on the same side of the curved section. I guess I'll see what you mean when it gets delivered. It has to be better than what I've got!

Simon

There are two different beasts being talked about here Simon. If you want to use a DTI for small holes, something like this is really helpful -
P1010936 (Medium).JPG P1010939 (Medium).JPG
Mitutoyo will sell you one (I think they call it a Zero-it), but this one was made from plans floating around the internet. One tip though is that it is better to use a vertical indicator like this one as you can see the dial more easily (A Stuart suggestion). I used mine today in fact for setting up something central on the R/T. These are used unpowered (rotate the spindle by hand)
IMG_0111.JPG

Coax indicators are usually used with the machine running - the X and Y slides are adjusted so that the needle deviation is at a minimum. The top name is Blake. I managed to pick one up second hand for the right price but I don't use it much mainly because they gobble up Z (from memory 150mm or so?). The dial has 5/10th's divisions which is the same as the vertical DTI pictured above.

Blake.JPG

PM me if you think it needs a short holiday...

Michael

Originally Posted by simonl

You turned up more than I found. $60 is probably justified but $30 for delivery (for such a small item) is a bit rich!

I've ordered both a M&W holder and the Hairy forbes holder. They should do me nicely.

Simon

A more economical version of the Noga - http://www.ebay.com.au/itm/On-Off-Sw...item19d22c4df5

I had two of these little blighters. Gave one away and mounted the other's arm on little pot magnet. Never tried it out as a concentic centring device though. No need really.

BT

Originally Posted by simonl

Hi Phil (steamwhisperer) you still out there? I (think) I understand the concept of using the edge finder. I have used it to find the centre of a dowel pin or shaft but not a hole. Assume the same but opposite? When you have it dead centre in say the X axis, any movement of the Y in either direction will deflect it off, then do same for Y axis?



Simon

Hi Simon,
finally got in
Doubleboost has a video on his channel on how to find the centre of a hole.
https://www.youtube.com/watch?v=R9cs...6NjtuIYI8OvPn1

Phil

Thanks Phil, I'll watch that once I offload the kids to school.

Michael,

Thanks for the offer of the coax. Not really needed now since I have all these other ideas now. Anyway, you have helped me more than you realise because I think I will make one of those alignment tools you posted a pic of. I have all the parts in scrap bin ready to be used!

Cheers,

Simon

Did you find the plans for it Simon? They are floating around somewhere. I have them i can email you if i can't find you a link. I'm sure Michael posted them but where.....

Ew

Wow that was easier than i thought... http://www.homemetalshopclub.org/pro...old/hldr1.html

Originally Posted by Ueee

Did you find the plans for it Simon? They are floating around somewhere. I have them i can email you if i can't find you a link. I'm sure Michael posted them but where.....

Ew

Wow that was easier than i thought... http://www.homemetalshopclub.org/pro...old/hldr1.html

I bought one of those from cdco...not good quality Mike