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Need some help measuring some parts.
- Thread starter vettedude
- Start date
- Replies 29
- Views 4,751
xdmp22
Hot Rolled
- Joined
- Jan 28, 2012
- Location
- Nebraska, U.S.A.
How good do measurements need to be? Calipers with a good feel while slowly spinning the part by hand can get you pretty close.....
Making an aluminum bar with multiple steps of sizes can be a good guage too....
Making an aluminum bar with multiple steps of sizes can be a good guage too....
Peter Colman
Stainless
- Joined
- Sep 22, 2004
- Location
- Rugeley UK
If you mean the cross section in the left picture, you will have to remove the spring, I would then take a slice and use a shadow graph. It helps if you freeze the part first to stiffen it up.
Gordon B. Clarke
Banned
- Joined
- May 29, 2010
- Location
- Denmark
You wrote "measure" but as you have several perhaps a check is OK? If so then I'd get two pieces of round material of a suitable OD. The material you use isn't really important and a hole in the middle is also OK.
You make one piece that has dimension A at max and B at min and one piece that has dimension A at min and B at max.
In other words Go NoGo gauges. You can also just use one piece of material and have the Go on one side and the NoGo on the other.
I can imagine you have reasonably large tolerances on the OD and ID so you should be able to measure the max and min of the gauge grooves with a caliper.
Gordon
I've made something like this more than once
You make one piece that has dimension A at max and B at min and one piece that has dimension A at min and B at max.
In other words Go NoGo gauges. You can also just use one piece of material and have the Go on one side and the NoGo on the other.
I can imagine you have reasonably large tolerances on the OD and ID so you should be able to measure the max and min of the gauge grooves with a caliper.
Gordon
I've made something like this more than once
Good thoughts from all. However using go and no go gages will be tough, as the part is soft and will deform to the gage, also the geometry is hidden. Calipers are too inconstant, i dont have that level of feel, and would drive myself insane with them.
Yeah this is a check to see if they conform to print.
Yeah this is a check to see if they conform to print.
Gordon B. Clarke
Banned
- Joined
- May 29, 2010
- Location
- Denmark
I'm not getting "... the part is soft and will deform to the gage ...." as that is the whole point of the gauge. It should "plop" into the groove in the Go gage but to go into the NOGo gauge would have to be forced.
You're holding back on way too much information if you want a useable answer. You said you had some ideas of your own. This would be the time to share
Gordon
Nick Mueller
Titanium
- Joined
- Jun 12, 2006
- Location
- Munich / Germany
As you need to measure the cross-section:
Cast it in transparent resin, slice it in thin sections and put it on an optical comparator (or measure it optically).
Hopefully, you don't have to inspect 100% of your work.
Nick
Cast it in transparent resin, slice it in thin sections and put it on an optical comparator (or measure it optically).
Hopefully, you don't have to inspect 100% of your work.
Nick
As you need to measure the cross-section:
Cast it in transparent resin, slice it in thin sections and put it on an optical comparator (or measure it optically).
Hopefully, you don't have to inspect 100% of your work.
Nick
This is what i was thinking of doing more or less, anyone have any advice on the resin and the comparator? I am not sure how i would section the part and still maintain dimensions.
xdmp22
Hot Rolled
- Joined
- Jan 28, 2012
- Location
- Nebraska, U.S.A.
Does your part have the coil in the middle? If so how much room is I
Between the coils?
I would also check into a custom snap guage....contact a few makers and tell them the possible thickness of material and the gap between the coil....also have ready the material spec like the durometer of rubber or plastic.....that will be needed to figure spring pressure
Between the coils?
I would also check into a custom snap guage....contact a few makers and tell them the possible thickness of material and the gap between the coil....also have ready the material spec like the durometer of rubber or plastic.....that will be needed to figure spring pressure
helterskelter
Cast Iron
- Joined
- Jun 27, 2011
- Location
- Dallas, TX
For the resin I would probably use something like Epofix from Struers, it's a cold curing slow setting resin that shouldn't deform your parts. The fast setting resins tend to shrink and possibly distort your geometry. You'll need to grind and polish your cross section.
Also consider how accurate you need to be because you need to make sure the cut face is square otherwise you're not getting the true cross section. What kind of tolerances are we talking about?
I personally would put it on a CMM. If you're working with tight tolerances it might be a good idea to send to someone capable if we're just talking about a first article inspection.
Heavey Metal
Banned
- Joined
- May 10, 2011
- Location
- Texas
Shadow graph with part installed on a mandrell.
no coil in the middle
I know CMM would do it, but i would like to avoid that, too expensive
Nick Mueller
Titanium
- Joined
- Jun 12, 2006
- Location
- Munich / Germany
Here is the cheap solution for the cheap people.
But don't laugh!Buy a (crappy) USB microscope. Magnification of 100 is more than enough. Somehow clamp it to your mill's spindle. Draw a crosshair on your PC's monitor. Move the table in X/Y to find the edges of all features while reading the DRO of your mill.
Distortions of the lens don't play a role, because you are measuring always at the same pixel. Magnification is not important, as long as you don't change it (including Z-height) while measuring.
You could even use some colored resin, as long as you can distinguish it from your part.
Nick
we did extrusion dies for making drinking straws
you would be surprised how finicky folks are about that
its all about material
aka
all about the money
in the end proper interior size was checked with a pin and the measure the od
this thing looks like a seal of some sort
can you get something that mimicks the spring in it
and the start slipping a pin through the id??
just a thought
you would be surprised how finicky folks are about that
its all about material
aka
all about the money
in the end proper interior size was checked with a pin and the measure the od
this thing looks like a seal of some sort
can you get something that mimicks the spring in it
and the start slipping a pin through the id??
just a thought
xdmp22
Hot Rolled
- Joined
- Jan 28, 2012
- Location
- Nebraska, U.S.A.
Could you use a snap gauge then? Or is there a solid rod in place of coil?
Im not totally understanding your part...but it seems a snap gauge either with flat face or ball end or one of each would do the trick for the cross section and then a go nogo like I and/or Gordon mentioned
bryan_machine
Diamond
- Joined
- Jun 16, 2006
- Location
- Near Seattle
So a real problem with a squish part like this is that you don't care so much about its dimensions at rest, you care about its dimensions when installed (or so I conjecture.)
A fancier variant of Nick's idea is to put the same or similar camera on tool maker's microscope or even a Kestral type - which with high mags can do some Z measurement as well. (Also works OK attached to your milling machine if the depth of field is narrow enough and you are patient enough.) Kestrel Elite measuring microscope - Patented toolmakers microscope
But assuming you want to check lots of these, you'll want some kind of go-no combination (see above posts) As in, it should be slip fit onto mandrel A, then slip fit into over-mandrel B, but not fit without lots of force into over-mandel C.
A fancier variant of Nick's idea is to put the same or similar camera on tool maker's microscope or even a Kestral type - which with high mags can do some Z measurement as well. (Also works OK attached to your milling machine if the depth of field is narrow enough and you are patient enough.) Kestrel Elite measuring microscope - Patented toolmakers microscope
But assuming you want to check lots of these, you'll want some kind of go-no combination (see above posts) As in, it should be slip fit onto mandrel A, then slip fit into over-mandrel B, but not fit without lots of force into over-mandel C.
helterskelter
Cast Iron
- Joined
- Jun 27, 2011
- Location
- Dallas, TX
What dimensions are you trying to capture and how many parts are you trying to measure?
The real Leigh
Diamond
- Joined
- Nov 23, 2005
- Location
- Maryland
Are you trying to measure the blue part in the illustrations, without the spring installed? What exact dimensions do you want?
A cross-section can be done optically, which is the most appropriate method for flexible parts.
- Leigh
A cross-section can be done optically, which is the most appropriate method for flexible parts.
- Leigh
