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View Full Version : Idea for a wiggler from edge finder



nheng
08-13-2009, 08:50 PM
I've been thinking about this since the thread on wigglers about a week ago.

A simple adapter to fit the end of a typical 0.200" edge finder post and holds a smaller diameter point such as a mechanical drafting compass point, could be used as a wiggler.

Some edge finders have a cone shaped end and while this can work, I've come close to destroying one several times by having it spin with the work (from too much pressure). This is the point of the smaller point, which should greatly reduce or eliminate the chance of spinning.

Den

nheng
08-13-2009, 09:08 PM
This took about 8 minutes in Alibre (mentioned in the "3D CAD on the cheap" thread). For simplicity, it is one solid part, not an assembly.

http://img.photobucket.com/albums/v319/nheng/machinery/wiggler_from_edge_finder-1.jpg

JCHannum
08-13-2009, 09:52 PM
Why not just use a Starrett 828 wiggler/center finder or one of its clones?

nheng
08-13-2009, 11:43 PM
I dunno, maybe more compact and cheaper if you don't have a wiggler already. Possibly could be better suited for tiny parts. I have one of the nice old Starrett 65s and one thing lacking in my idea is the "magnification" that the 65 could give you with a short/long rod combination. The newer wigglers don't have this either, do they?

Black_Moons
08-13-2009, 11:45 PM
I got my wiggler set for like $15.. doesnt get much cheaper then that.. works well as far as I can tell.

beanbag
08-14-2009, 12:05 AM
why not put your wriggler on the lathe and cut it down?

oldtiffie
08-14-2009, 12:17 AM
I agree with Jim Hannum.

Here's the Google search result:
http://www.google.com.au/search?hl=en&q=Starrett+828+&btnG=Google+Search&meta=&aq=null&oq=

If its only the pointer and you need it sooner rather than later, just use a 2" or 3" nail. Turn/file a part of a ball on the "big" end and a reasonably "slow" pointed taper on the "pointy" end of the nail.

Hold lightly in your mill spindle chuck or collet, spin at ~1,000RPM, put the back of your thumb nail onto the pointy end and push lightly with the back of your thumb nail until the point is "true" (by eye aka visually) and away you go - with a simple pointer accurately aligned to the spindle axis.

Buy a Starrett or a clone as they are very useful and are quite cheap.

dp
08-14-2009, 02:02 AM
I'm not sure I know what your goal is - the problem you're solving. A wiggler is used to create an absolute zero run-out pointer. You can put a wiggler in the ugliest nastiest chuck and spin it to zero run-out and keep it there. That zero point is directly under the center of the spindle.

An edge finder is intended to do just that. Part of what makes it work is the greater than zero swept surface of the moving tip such that the tiniest pressure creates an exaggerated response. That surface is one tip radius away from the center of the spindle.

These are unrelated purposes. The fine tip in your drawing is not held fast as would be the case for a wiggler, and hasn't enough swept surface to produce exaggerated responses as an edge finder.

Color me perplexed - it's probably something I'm not understanding.

JCHannum
08-14-2009, 07:38 AM
We might be talking past each other. The pointed end of an edge finder is not meant to be used in contact with the part or with it or the part in motion. It is used to locate scribed lines or center pips.

If this is what you are trying to accomplish, a finer point would be convenient at times on small work. Frequently, broken end mills or reamer shanks, for instance, will be ground to a point for this purpose. The drawback of the edge finder is its short length which makes it difficult to see just where it is. The additional length of the shopmade items overcome this to a degree.

nheng
08-14-2009, 08:21 AM
JCHannum understands me but I can see that my intent wasn't very clear. I was thinking of placing the tip either at the intersection of scribe lines or pips from a punch while the part is in a 4 jaw chuck or on a mill table.

It was also intended for small parts and the small size might also be an advantage on a small lathe like a Sherline, Taig or 7x12.

The idea popped up when I had to re-assemble my Starrett edge finder after it twisted apart from pressing the cone end too hard into a heavy center punch pip. Den

JCHannum
08-14-2009, 09:12 AM
The fixed center point such as this will work reasonably well when used in a drill press or milling machine as it is installed directly in the spindle, the axis of rotation of that machine. When installed in a tailstock, it will only be as accurate as the tailstock plus whatever is used to hold it. There are several sources of error that can stack up if used in this manner. It will get you close, but for best accuracy, further dialing in will be necessary

The #64 wiggler is an improvement on this as it references only the center pip. When adjusted to zero or minimal movement, the center pip is center with the axis of rotation of the lathe spindle.

Frank Ford
08-14-2009, 09:22 AM
I made this gizmo before I knew about wrigglers. It's a simple center with a hardened point that has a long skinny shank and MT2 on the back end to stick into the tailstock.

http://www.frets.com/HomeShopTech/Tooling/WigglyCenter.jpg/wigglycenter02.jpg

Once I stab it into the center mark, I use my indicator just the way I would center anything in the 4-jaw.

http://www.frets.com/HomeShopTech/Tooling/WigglyCenter.jpg/wigglycenter01.jpg

gnm109
08-14-2009, 10:41 AM
I got my wiggler set for like $15.. doesnt get much cheaper then that.. works well as far as I can tell.


CDCO has center finder kits with a chuck and four tips for $6.00 and edge 3/8" X .200 edge finders for $5.00. They work very well also.


.

JMS6449
08-17-2009, 06:21 PM
Center punch and wiggler. If you want accuracy use toolmaker buttons,
search, there are old discussions about these.