# edge finder



## speedhound (Sep 8, 2010)

Hi, im thinking of buying a touch point edge finder thing something cheep around £25 are they any good and if so which one is best.
Thanks


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## Jasonb (Sep 8, 2010)

I use mine all the time and find them very accurate, get a shank that will easily fit a common collet, I use a 1/2" one. And they don't work with plasticas as the part needs to be able to conduct electricity.

Got mine from Greenwood Tools but can't see them on their site now.

Jason


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## Blogwitch (Sep 8, 2010)

MSC/J&L have one left in their stock clearout.

Starrett quality

http://www.mscjlindustrial.co.uk/STC-56041H/product.html#

I have no idea how this type works, but sounds good by looking at the extra info.


Bogs


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## Jasonb (Sep 9, 2010)

Bogs I think thats to set you tool height not an edge finder. It works by completing the circuit as the cutter touches the top of the tool and lights up, the tool is an exact height say 2" above the table so you then set your Z axis to 2".

Jason

EDIt looks like the picture or description is wrong, as search for the Starret 827MA comes up with this which is an edge finder
http://www.toolbench.co.uk/Starrett-827MA-Edge-Finder--Single-End-10mm-PSTR827MA/
Also if you tend to work in imperial get one with a 0.200" tip as its easy to workout the offset, trying to do it with a 6.0mm tip may be a bit of a pain


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## Blogwitch (Sep 9, 2010)

Jason,

I have had an imperial Starrett for well over 20 years, and is still as accurate today as the day I bought it.

I noticed that as I was browsing thru their massive clearance list. If it is a tool height setting one then that is a real bargain, because the cheapest I have seen was about 70 squid.

John


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## mudbug (Sep 9, 2010)

I've had one like this for years. I find it works just as good as the expensive ones.

http://www.use-enco.com/CGI/INSRIT?PARTPG=INSRAR2&PMAKA=636-7034&PMPXNO=942655


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## shred (Sep 9, 2010)

Bogstandard  said:
			
		

> I noticed that as I was browsing thru their massive clearance list. If it is a tool height setting one then that is a real bargain, because the cheapest I have seen was about 70 squid.


Yeah, I've got one of those height-finders a friend gave me.. looks identical to the pic but doesn't say 'Starrett' on it anywhere. It works well, especially after I banded an alligator clip and a foot of wire to the base for use on non-conductive materials. Clip the wire to the tool or machine somewhere in that case. 

I'm not sure why they cost so much though; it seems like it would be pretty easy to whack one up and surface-grind the tip to set the height.


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## Majorstrain (Sep 9, 2010)

I made one a while ago because as Shred said, they seem to be over priced for what they are.

Here is the topic link. Just in case you got the urge to make one.
http://www.homemodelenginemachinist.com/index.php?topic=5218.msg53889#msg53889
PDF file attached to the first post

It's sprung so that if you lower the cutter too much you don't damage the cutter. It could be used on a CNC but it was designed for a manual machine.
It has a buzzer instead of an LED

Cheers,
Phil


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## don-tucker (Sep 9, 2010)

Of course there is always the 1/4" dowel and a bit of fag paper  ;D
Don


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## firebird (Sep 9, 2010)

Hi Speedhound,

I have one of those edge finders and got on fairly well with it until the day I wound the table the wrong way and bent it. With a lot of care and patience I managed to straighten it out again in the lathe using a dti. About 2 years ago I treated myself to a laser centre finder and I absolutely swear by it. They are deadly accurate and can also be used for picking up centre punch dots as well as edges and of course you don't have to worry about halving the reading, where ever the laser dot is just zero your dials. They are not cheap however but to my mind worth every penny. Heres a link to one company that sells them (usual disclaimer)

http://www.chronos.ltd.uk/cgi-local..._Touch_Point_Sensors___264.html#aLCEFP#aLCEFP

heers

Rich


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## speedhound (Sep 10, 2010)

Hi, i was orginally going to get a lazer one but i decided to cheep out and get a touch point one, probilly from chronos.
Thanks


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## Joachim Steinke (Sep 10, 2010)

Hi folks

I know you are primarily discussing the aspects of touch point edge finders here, but I want to take the opportunity to show you another (definitely not new) approach to the theme finding edges on the milling machine.

I have, like many others of you, a variety of conventional mechanical edge finders in my shop for several years now









but since I made my own finders based on simple ball bearings the commercial ones are very seldom in use.

To make this type of edge finder you only need two things, a suitable ball bearing and a true running shaft. For the shafts I like to use ground dowel pins, they are straight enough for this job and have a precise diameter. Our German dowel pins with m6 fit have nearly no clearance to a ball bearing hole. So normally you get a slight press fit from only pushing them into the bearing and this will fix things strong enough. But needles to say you can use any sort of straight self turned shafts also and if you have problems with a precise press fit to the bearing a drop of Loctite might help a lot.








To me that sort of edge finders have several advantages:

They are cheap and easy to build, so you can make a whole assortment of that useful helpers for different shop tasks. Most of you will have all the needed components in your drawers anyway.

You can make several edge finders with different shaft diameters of your main collet sizes, so you dont have to change collets so often when using a variety of tooling on the mill.

Ball bearing finders work proper in a wide range of spindle speed, you can use them up to 4000 rpm and even more without any problem. This can be very useful on machines without variable speed control, no more drive belt altering when changing to the edge finder while you are on high speed milling operations.

And the edge detection is really precise and easy to read, to my experience +/- 0.01mm (0.004in) ore even better is always reproducible. 

To get an impression how it works you can have a look at this little video, the mill is running with 3000 rpm at this time: 

http://pl-hi.de/JST/Ball-Bearing-Edge-Finder-01.mpg

And here is the scenario for another video using a dial indicator 








to demonstrate the reproducibility when getting in contact with the surface of your work piece. The counter has a graduation of 0.01mm. 

http://pl-hi.de/JST/Ball-Bearing-Edge-Finder-03.mpg


Good Night

Achim


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## SAM in LA (Sep 10, 2010)

Achim,

Very clever.

Thank you for sharing.

SAM


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## Lew Hartswick (Sep 10, 2010)

SAM in LA  said:
			
		

> Achim,
> 
> Very clever.
> 
> ...


Yes too bad the links don't run. 
  ...lew...


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## cidrontmg (Sep 10, 2010)

Lew, I think it would be a good idea to d/load the video files to your machine first, and watch from there. That way, they work just fine. The first is 2.1 Mb, the second is 3.85 Mb, so with any decent broadband, it´s just an instant to d/load..


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## Majorstrain (Sep 11, 2010)

Very impressed Achim, :bow:
I'll have to make some of those.
Cheers,
Phil


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## Peter. (Sep 11, 2010)

I like those too - thanks for posting it up!

Lew, the links run fine for me using GOMplayer.


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## Joachim Steinke (Sep 11, 2010)

Good morning

Sorry if some of you have problems with my videos.

I have just uploaded them to you tube, here are the two links:

[ame]http://www.youtube.com/watch?v=gNjrUaS9q1I[/ame]

[ame]http://www.youtube.com/watch?v=kWl8Qrlbj_Y[/ame]

I hope this might help a bit.

Achim


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## tel (Sep 11, 2010)

The links work OK for me as well. Excellent idea - I'll be hunting through my bearing drawer first thing in the morning! Thm:


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## GailInNM (Sep 11, 2010)

Thats a great idea, Achim.
Thanks. 
I could not get the original video to open either but the Utube video works fine.
Gail in NM


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## freemen (Oct 1, 2010)

Thanks, you just saved me 20$ from buying one on fleebay and now I can make 4 or 5 of them for different size collets. :bow:


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## krv3000 (Oct 1, 2010)

HI good work  from bob


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## El$syd (Oct 4, 2010)

Thanks for posting this excellent idea - absolutely brilliant, I hope to make several!
But I am surprised no-one makes these commercially!!!! ???


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## petertha (Apr 23, 2012)

Joachim Steinke  said:
			
		

> And the edge detection is really precise and easy to read, to my experience +/- 0.01mm (0.004in) ore even better is always reproducible. Achim



Hi Achim. That is such a neat device.

Did you mean 0.01mm =* 0.0004*"? (one more zero).

Is there a certain class or spec of bearing that should be used?


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## pkastagehand (Apr 24, 2012)

I have always used either the wiggler edge finders (or the end mill and paper trick if I didn't want to remove the cutter and put in the edge finder). I don't see that it makes much difference except to the wallet whether I use old tech or new tech, and being a frugal sort (don't say cheap ;D) I like the old tech. If desired accuracy is reachable there is no advantage if you have to remove the cutter and put in the edge finder no matter what style you use. Even the ability to center on a punch mark instead of an edge is doable with "old" tech wigglers. 

I recently made one of those ball bearing jobbies and will make some more as time and need demand since it would be nice to have different sizes for different jobs/collet sizes.

When people rush out to buy the "newest" gizmos I sometimes wonder if they have more money than sense. I'll agree that at times new can be better but many times it is marketing people creating a "need" that didn't exist until they created the new device to fill the "need". And if it makes more jobs and keeps the economy going it isn't all bad I suppose.

Paul (not quite a luddite but showing my age?)


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## picclock (Apr 25, 2012)

I have some of the ball bearing type edge finders I made before getting a starrett type. One thing I found which made them easier to use is to paint the top bearing shield black and then use tippex to make white segments. This gives a much better indication as to whether the bearing is rotating. 

However I jumped ship for a Starret for two reasons. Size matters ;D at least it does for me. The size of the end of a Starret edge finder is smaller than any of the ball race versions I made. This means I can get a centre off of any small hole >6mm dianeter., And then there's the other end. Its a concave conical shape and will allow one to get a centre position from any size hole <10mm or even a centre punch mark. When I first received it I wondered what I would use it for but its since proved its worth many times over. Its only as accurate as your fingers, misalignment being determined by feeling the difference between the shaft and the conical end. I can easily get to <1thou using this. Its easy to see the runout of toolholder just by rotating the spindle half a turn after alignment, so if you want to be really picky I guess you would set the position to the average of the two aligned readings.

Best Regards

picclock


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