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View Full Version : Need info on Co-Ax indicator



mikep379
10-16-2009, 05:23 PM
Has anyone ever used the cheap co-ax indicator off of Ebay.The name on it is Shars and i am sure that it is made in China.The price on it is around $40 and was wondering if it is worth buying or not.Thanks

lazlo
10-16-2009, 05:43 PM
They're OK. I have one, and a real Blake, and not surprisingly, the Blake is a lot more accurate, but the Shars copy is fine for home-shop use.

Just check the ring at the top that the indicator pivot rides on. The Blakes are lapped smooth, and some of the Chicom ones can be rough and/or off-axis with the indicator body. Relatively easy to fix though.

The other nice thing about the Chinese clones is that they come with the complete set of feelers, which you'll definitely use. The stock Blake only comes with two short feelers, and sadly they're not interchangeable.

Michael Moore
10-16-2009, 06:00 PM
Blake will do service on their Co-ax indicators. After 25+ years mine was getting sticky so I recently sent it back to them for a cleaning.

cheers,
Michael

Bill Pace
10-16-2009, 06:16 PM
Have had one that I got from Shars for a couple years and it performs quite well -- this is in my home shop, mind you. Would think that if are also in a home shop situation it would be fine for that. --- sure hard to beat the price! ;)

S_J_H
10-16-2009, 06:30 PM
I have one of the import co-ax's. The body is actually made pretty good. Clearances are tight and movement is nice. Where they dropped the ball is using the typical bottom of the barrel gauge. The feelers are pretty cheaply made as well.

I think there are plans on this site to build one, which could be a nice project.

motorworks
10-16-2009, 07:46 PM
I have two in the shop that I use daily. (make in china type)
They work well and have stood up so far.
e2die

MickeyD
10-16-2009, 08:40 PM
I have a Blake and a Shars one. My advise is to save your money and buy a new Blake or take some time to find a nice used one. The Shars one is not horrible, but nowhere as smooth and accurate as the Blake is.

Walter
10-16-2009, 10:37 PM
I own and use a Blake, I'd not even consider a cheap version for something like that. Just my opinion.

Boucher
10-16-2009, 10:38 PM
I bought a Fowler. It works but is not very user friendly. The small screws are sorry. Some I have managed to replace. I wish that I had waited and bought Blake.

ahidley
10-16-2009, 10:55 PM
I have one from shars, works great.

Don_Hartman
10-17-2009, 01:50 AM
In over 20 years of working in a tool room at a few different companies I have never seen anyone using them. A few people had them and never used them. The complaint was the length in the Z axis they took up, 1/8 was the smallest hole that could be indicated without modification to the tip, unable to work close to a shoulder, high cost for a one use tool. Also picking up a hole/or pin is only half the setup. Getting the machines backlash and repeatability of that pick up is the other half. That requires a move away and back to verify and adjust for that. Even with ball screws that is a good practice.

So could some one explain the reason for the apparent following of these Co-Ax on this list? I currently work with a few life long toolmaker and they grab there Interapid or B&S indicators 100% of the time.

I also use my indicator... Chances are you already have it in the spindle to check your vise or verify your work is sitting in the vise right and square. Move over to your hole or pin. Work parallel to the machine axis and one axis at a time.

Steps to pick up a hole or pin.

1)Zero the indicator on one side of the pin/hole with the indicators action parrell to the first(x)axis . Note table position on dial or on DRO.

Rotate the spindle (indicator) 180 degrees; move axis(x) till indicator reads zero note distance the table has been moved. Move table back half that distance.

2)Repeat the above but for the other (y) axis.

3)Reposition indicator point to contact work . Now you can sweep about the spindle axis making any minor adjustment needed.

4)Zero DRO or dials move from zero position then back eliminating back lash to check pickup.

It helps if when sweeping a hole that the indicators swing is less than the hole and a larger swing on the pick up of a pin. Also machine backlash has been ignore in all but the last step above but will need to be addressed through the pickup.

Don

loose nut
10-17-2009, 02:00 PM
Don, If you look at the way a Blake indicator works it is primarily the same as the way you described the use of a ordinary indicator, only the dial doesn't rotate so it is a bit easier to use. You have the same backlash problem with a regular indicator as you do with a Blake type, it is just a bit easier to work with, more so on smaller "head room challenged" bench mills found in home shops. Your old time toolmaker may not use them because old dogs don't like to learn new tricks, that doesn't mean newer ideas aren't good too.

lazlo
10-17-2009, 04:19 PM
In over 20 years of working in a tool room at a few different companies I have never seen anyone using them.

Here's I'm using a Blake to pick up the hole on a rotab:

http://i164.photobucket.com/albums/u15/rtgeorge_album/Servo%20Plate/Blake.jpg


The complaint was the length in the Z axis they took up, 1/8 was the smallest hole that could be indicated without modification to the tip, unable to work close to a shoulder, high cost for a one use tool.

All true.

But they're great for picking up large holes or cylinders that are bigger than the sweep of a typical DTI. The alternative in that case is to use a Zero-Set type indicator holder, and then you need to use a mirror...

John Stevenson
10-17-2009, 04:37 PM
Use one of these.

http://homepage.ntlworld.com/stevenson.engineers/lsteve/files/3dtester.jpg

Insert into collet, do not start spindle.
Move to side of hole until needle reads zero, set DRO or dial. wind to other side to read zero and take reading, half that and go there then lock that axis.

Then without moving the gauge do the other axis. the needle wiil work in full 3d mode, you can even do the Z move all at the same setting.

Even easier to pick edges up.

http://www.youtube.com/watch?v=RTzxebz9xkQ&feature=related

Once you have used one of these you won't bother with a DTI or co-ax ever again.

.

S_J_H
10-17-2009, 06:55 PM
Use one of these.
I was going to bring those up earlier..

John, have you ever seen the inner workings of these devices? A co-ax tool is actually a simple device to make, if of course you purchase the gauge.
I'm just wondering if the 3d "taster" is something the HSM could try and copy for his own use?

Steve

clutch
10-17-2009, 07:15 PM
We have both the Blake and the Enco MHC clone in use where I work. Both seem to function fine, they pass periodic calibration, I've used both out in the tool room,setting up the bridgeport, and out on the production floor setting up fixture offsets after a crash or rebuilding a work holding device used in our VMC's.

I'd have loved to bought the Blake for myself but my finances, considering the differences in both, lead me to the MHC clone.

If I have to get things dead nuts, I can always mount a test indicator to increase accuracy as the last step. Since a test indicator has 0.008 to 0.016" range, you need to rough center before using one if your tolerances are tight.


Clutch

lazlo
10-17-2009, 07:16 PM
Use one of these.

http://homepage.ntlworld.com/stevenson.engineers/lsteve/files/3dtester.jpg

Once you have used one of these you won't bother with a DTI or co-ax ever again.

Funny that you mention that John. I just nabbed a real Haff & Schneider 3-D Taster, NIB for $150 :D

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=280406455544

http://www.haff-schneider.de/index.php?article_id=78&clang=1

Roy Andrews
10-17-2009, 08:59 PM
i'm with john. i got one of those in a machinists box from an estate sale of a friend. i knew it was in there and really wanted that box. it went very cheap and after the auction i gave his wife extra. i use it a lot and really like it.

BobWarfield
10-17-2009, 09:06 PM
The tasters are cool, but if you have a Mach3 CNC, it's hard to beat an automated touch probe.

Push a button and it locates the edge, center of hole, tool height, or whatever.

Easy to wire up and very cheap. I quit using both my Blake and Taster once I got that done.

Cheers,

BW

Spin Doctor
10-17-2009, 09:28 PM
One of the Tasters is as close as you can get in manual to a touch probe. The Blakes pretty good. Lets face it .0005" is close enough for most stuff. The imports just aren't as good. I know I have both. One really nice place for a Co-Ax is on a jig mill or horizontal boring mill. Not something you see in the average home shop :D. Funny story. We had a guy at work who had to check the location of a bushing plate to the spindles in a multi spindle drill head. He had the bright idea that he'd use his co-ax. Fine in theory until he had the electrician by-pass the interlocks and power up the head.


KABOOM!!!!!!!!!

Co-Ax indicators tend to gernade at 3000 RPM. I'm at a diferent company now and he works there too. When I want to zing him a little I ask if I can borrow his Blake. :D