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+--- Thread: Inspecting and comparing parts (/thread-2224.html)
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Inspecting and comparing parts - PixMan - 08-07-2014
So the part I made using a print sent by the machine manufacturer appears to be either:
1) Out of specification
2) Not the same part as the old one
I pick No.2! I know I made the features all within the dimensions and tolerances given on the print, so let's find out why it doesn't fit.
First, Darren told me that the new part doesn't seem to sit flat into the mating part, the milling head for his Kondia. OK, start by measuring the height of the Ø43mm boss that centers the part.
A depth micrometer is the right tool for the job. Turns out the original part is 0.066" (1.676mm) lower than the new one. Easy fix, mill the thing off! Let's check a few more things first.
![[Image: IMG_20140804_143023995_zps7jt074oc.jpg]](http://img.photobucket.com/albums/v466/kenm10759/Dads%20shop/IMG_20140804_143023995_zps7jt074oc.jpg)
Next, I notice that visually the depth of the Ø38mm counterbore appears deeper than the new one. Set both parts up on the back datum surface and place a short ceramic "parallel" I have into the counterbores. The new one was made to 14.30mm per print, the old one is 14.45mm. I can't make that thicker, so a .006" shim is easy if needed.
![[Image: IMG_20140804_142910089_zps91bh1vuw.jpg]](http://img.photobucket.com/albums/v466/kenm10759/Dads%20shop/IMG_20140804_142910089_zps91bh1vuw.jpg)
Darren reported that the two M6x1 socket head cap screws didn't quite line up. First check is the easy one; use a digital electronic caliper. No pics of this, but just check to make sure both holes are the same size (they are), "zero" the caliper within one hole, measure across both, 45mm center distance. The part print I worked from said 44mm, that's what the new part is.
Now to check the distance of those two holes as measured from the datum. The center of the Ø14mm bore is that datum, so set it up with two pins (drill shanks work fine here) to locate the part along the top of my "deadnuts" good angle iron, a pin I'd made into the Ø14mm bore.
Using a good old-fashioned Vernier height gauge, touch the top of the Ø6.5mm drill shanks, take the reading and subtract 1/2 their diameter. Now touch the top of the Ø14mm pin, take the reading and subtract 7mm. The difference between the two readings/centers is that distance I need. New part made to print it's 19.25mm. Measurement of old one, 17.25mm. This agrees with Darren's assessment of "the holes on the old one seem closer to the bore."
![[Image: IMG_20140805_210900398_zpsasq3qqva.jpg]](http://img.photobucket.com/albums/v466/kenm10759/Dads%20shop/IMG_20140805_210900398_zpsasq3qqva.jpg)
Some concern was expressed about the location of the long Ø16mm bore in relation to the other features. That was a challenge to measure mainly because the bore in the old part is extremely worn, and the mating part (which I'm glad Darren sent along) is also worn though only by 0.001" or so, and not the whole length.
By checking the height over the sliding part at both extremes of the play, I determined that if averaged out the new part was exactly the same as the old one in that respect.
![[Image: IMG_20140805_211809556_zpsbkf1ojrd.jpg]](http://img.photobucket.com/albums/v466/kenm10759/Dads%20shop/IMG_20140805_211809556_zpsbkf1ojrd.jpg)
Sorry for the fuzzy pictures, all were taken with my cell phone and I apparently didn't clean the lens very well.
In the end, they're close but not quite and it looks as though I should just try making Verson 2.1, as soon as I get more material. The deal breaker on just altering the new one is that hole location. Because the two holes are 1mm further apart and 2mm closer to the datum in the other plane, there's just not enough "meat" there to move the holes. I thought to make plugs and weld them in, but the old part is also 1mm wider overall and I'd need to build up the sides in a few places.
Perhaps you can see what I mean in this view.
![[Image: IMG_20140805_213318712_zps6z0gskj4.jpg]](http://img.photobucket.com/albums/v466/kenm10759/Dads%20shop/IMG_20140805_213318712_zps6z0gskj4.jpg)
I'll be metal shopping over the course of the next week and hope to make the new one next weekend.
RE: Inspecting and comparing parts - EdK - 08-08-2014
Thanks for explaining how you did the measurements. That's immensely educational.
Ed
RE: Inspecting and comparing parts - Mayhem - 08-08-2014
Exactly what Ed said - Thanks Ken.
RE: Inspecting and comparing parts - DaveH - 08-08-2014
I think you have done well there Ken.
I would still be searching where I threw it.
DaveH
RE: Inspecting and comparing parts - Mayhem - 08-08-2014
Sorry - I forgot to mention that I'm happy to plug the holes on the head and then drill new holes and tap to suit the part. This would mean that all that is needed is machining the boss.
RE: Inspecting and comparing parts - PixMan - 08-08-2014
(08-08-2014, 06:08 PM)Mayhem Wrote: Sorry - I forgot to mention that I'm happy to plug the holes on the head and then drill new holes and tap to suit the part. This would mean that all that is needed is machining the boss.
I had considered asking our mutual friend Jennifer (allescence username here) to do that, but it won't be enough. Because the old busted up one is 61mm wide and the one I made to print is 60mm, the two angled sides are also the wrong angle and would need a lot of build-up. I don't thin it's worth it because starting from a new block of material wouldn't take much longer than that whole process and you'll have a clean, solid part with no welds.
(08-08-2014, 12:49 PM)DaveH Wrote: I think you have done well there Ken.
DaveH
Lost in translation Dave. Do you mean you would have just heaved the made bad one toward the nearest large body of water?
BTW Darren, what do you suppose the shiny spot on the surface of the Ø43mm boss is from? Is that in contact with a rotating part or something? Should I be concerned about getting that height absolutely EXACT to the old one?
RE: Inspecting and comparing parts - Mayhem - 08-09-2014
Ken - I meant that I would plug the tapped holes in the actual head, not the part. That way, I could use a transfer punch to locate the position of the holes in the bracket to the head, drill and tap M6x1.
The conical gear that provides one of the feed directions (cannot recall which) sits against the hub. I think we should shoot for the same dimension on the hub, otherwise the gear may not mesh correctly.
RE: Inspecting and comparing parts - PixMan - 08-09-2014
Darren,
It would not be advised to plug tapped holes in the cast iron head when you'd have to drill and re-thread into the plugs. I could see where re-drilling could wander and end up with a broken tap or holes far off center. Really better to just make a new one and make it closer to the part you have.
The problem may have been in the print version. I notice now that there are no revisions to the print dated September 26, 1973. Chances are that your machine came a few months later and they'd identified problems in assembly so made changes to the parts. A pre-ISO 9000 compliant system means revisions can get lost. I think that's what happened here.
RE: Inspecting and comparing parts - Mayhem - 08-09-2014
You're just looking for an excuse to make more chips...
I was under the impression that my mill was circa 1970 but that has never been confirmed by Kondia. Anything is possible though.
RE: Inspecting and comparing parts - DaveH - 08-09-2014
(08-08-2014, 07:20 PM)PixMan Wrote:(08-08-2014, 12:49 PM)DaveH Wrote: I think you have done well there Ken.
DaveH
Lost in translation Dave. Do you mean you would have just heaved the made bad one toward the nearest large body of water?
Dead right
followed closely by the drawing 
DaveH