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  • Measuring inside grooves

    How do you measure to depth and width of an inside groove? I am building a hydraulic cylinder gland and need to measure the seal groove. 2 3/4" bore, groove will be say 3" diameter and 1/4" wide. Obviously no place for sloppy work so how do I get it right the first time? This is a one time deal so would rather not buy too many expensive tools to complete it.

  • #2
    On a 1/4" wide groove an inside mic is what I use. Regarding width you should be able to get close enough for hydraulic work with the back end of your calipers. This is assuming the groove is near the open end of the cylinder. If you need tighter width measurements, gauge blocks.
    Southwest Utah

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    • #3
      Use an inside spring caliper to measure the diameter. Expand it so it just touches the widest point, compress and pull it out, let it expand again and measure it with a mike or dial/digital caliper.
      For the width, you could buy a $15 digital caliper and cut off the outside jaws to fit it in the tube.

      https://www.ebay.com/itm/15218000550...sAAOSwdzVXlTwM
      Kansas City area

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      • #4
        This is the groove for the rod seal in the gland. The gland will be 1 1/2" thick and the groove will be centered in the thickness. 2-3/4" is not big enough to get calipers in. Although I just had a brain wave that I could cut the outside jaws off a cheap set to get this done. Inside mic should work for depth, I haven't used one in so long I forgot I had them. I don't have gauge blocks and probably don't need that level of accuracy anyway

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        • #5
          I'd start with a telescoping gage if the tips will fit in the groove. If not, I would take a couple ball bearings and place them in the groove with stiff grease to hold them and then measure over the balls with a caliper or preferably a telescoping gage or inside mic. A pair of 3/16" balls can be had from most decent HW stores pretty cheap.

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          • #6
            Originally posted by Toolguy View Post
            Use an inside spring caliper to measure the diameter. Expand it so it just touches the widest point, compress and pull it out, let it expand again and measure it with a mike or dial/digital caliper.
            For the width, you could buy a $15 digital caliper and cut off the outside jaws to fit it in the tube.

            https://www.ebay.com/itm/15218000550...sAAOSwdzVXlTwM
            My own outside spring style calipers are straight legged with just short "feet" at the ends. Perhaps it would be the right time to bend them for a little more depth into the grooves if needed. But the idea is certainly sound.

            If the thimble on the screw isn't a little stiff be sure to pinch the thimble and screw as you spring the legs in to extract the calipers and don't release the grip until the legs are sprung back out. A slight movement is far too easy otherwise.

            And since it's very much a touchy feely sort of thing you'll likely want to practice on a known size good smooth bore first. There was a thread a year or two ago about using spring calipers as an option to telescoping gauges. I got all enthused and tried it myself. It took a dozen or so tries to get the right feel and consistency. But once you get the right feel for the calipers being in contact you can nail the readings. It was likely 12 to 15 learning attempts before I was able to get readings that were all within a thou of the right size. About the same as it takes to learn to nail the right feel with telescoping gauges. Old world skillzzz.....

            Reading down the first few posts I was thinking cheap pair of calipers and cutting the outside jaws as well. Looks like there's a number of us that think the same way....

            Another option would be to make up a set of pinch calipers for doing the width of grooves on ID's just like you're doing here. At the most basic the two parts might look like this sketch. To use them just slide one past the other so the two straight parts of the tips touch the edges of the groove. Pinch to hold the setting, remove and measure. Extras to allow sliding and locking can be added to suit. And size could be adapted to fit into some pretty small bore sizes.

            Click image for larger version

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            Chilliwack BC, Canada

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            • #7
              Here is a simple way to check groove location. Make a washer .200 wide 3/8 dia and ream it to fit your depth gage rod. Put washer on depth mic rod extended out from depth mic base holding it to rod with set screw. Now with depth mic rod extended about an inch longer then what you need to check groove location you use a gage block to set washer a set length from depth mic base. Now that you know washer face location you can use reading on depth mic to check groove width and location.

              Click image for larger version

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              • #8
                Originally posted by gzig5 View Post
                I'd start with a telescoping gage if the tips will fit in the groove. . .
                How are you going to get the T-gauge out of the groove to measure it?
                Southwest Utah

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                • #9
                  Toolguy, you and I had the same brain wave at the same time apparently. Your suggestion to cut off a calliper was not there when I was composing my post. Great minds apparently πŸ˜ƒ

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                  • #10
                    Indical, is a cheap ??.. tool that could work for you. They come with different tips. Mueller gage is very expensive but nice. I have used ball bearings too. Click image for larger version  Name:	IDC_010_indical_o_ring_internal_groove_gage__76700.1447780227.1280.1280__67024.1447780720.jpg Views:	0 Size:	192.7 KB ID:	2000061
                    Last edited by Fasturn; 05-09-2022, 06:59 PM.

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                    • #11
                      Some other tools for checking grooves. Costly but if you are doing lots of grooves it’s β€˜t worth it. I ran thousands of grooves so I bought or made all.

                      Click image for larger version  Name:	DA69C41F-C5ED-49CB-9926-E283054082AF.png Views:	27 Size:	579.5 KB ID:	2000063 (jiio
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                      Last edited by jimsehr; 05-09-2022, 08:53 PM. Reason: Indical gages are now selling for $250 bucks. See post #10 think I paid about $40 bucks when I bought mine.

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                      • #12
                        I use a groove micrometer, it has pins not jaws, fairly basic thing, mines Moore and Wright but starret and brown and sharp do better ones ( imho)
                        chopping a cheap vernier is probably your best option, the grove mic I bought was about Β£60, not terrible but not cheap ( I did one using a carpenters Mort ice guage, use the two pins and measure over them, crude but works, remove the stick to leave just the staff, stem or whatever the long square bit is called.
                        mark

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                        • #13
                          Others beat me to my recommendations: the Mitutoyo Groove Mike (I got a like-new one on eBay awhile back for $120, good ones now go for $150 β€” $200, new ones $225 β€” $400 depending on the reach and range; there is one NOS with a rotating spindle and the larger diameter shaft currently listed for $1,000!!!), this is what mine looks like:

                          Click image for larger version

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                          and the Indi-Cal (eBay also for around $90 in VG condition, the quality of used ones varies greatly, but a bunch are currently listed) – you supply the DTI:

                          Click image for larger version  Name:	Indi-Cal in Box.jpg Views:	0 Size:	43.5 KB ID:	2000145

                          Click image for larger version  Name:	CACC Indi-Cal on Stand.jpg Views:	0 Size:	605.5 KB ID:	2000146
                          The base comes flat and is maybe 12 gauge steel: it took some head scratching to get it bent into shape without messing it up.

                          Parts for the Indi-Cal are getting scarce as the original company is closing down – pm me if interested in buying a new complete set (no boxes available) or parts at significant savings directly from the owner (I do not get anything from this, just trying to be helpful; I would post the contact info but have been asked not to by the owner).
                          Last edited by ChazC; 05-10-2022, 11:39 AM.
                          Avid Amateur Home Shop Machinist, Electronics Enthusiast, Chef, Indoorsman. Self-Proclaimed (Dabbler? Dilettante?) Renaissance (old) Man.

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                          • #14
                            Originally posted by chipmaker4130 View Post
                            How are you going to get the T-gauge out of the groove to measure it?
                            Exactly. There has to be enough width to rotate the tool back out. May not work with a standard tools, thus the alternative.

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                            • #15
                              Originally posted by Captain K View Post
                              How do you measure to depth and width of an inside groove? I am building a hydraulic cylinder gland and need to measure the seal groove. 2 3/4" bore, groove will be say 3" diameter and 1/4" wide. Obviously no place for sloppy work so how do I get it right the first time? This is a one time deal so would rather not buy too many expensive tools to complete it.
                              KISS Principle . If you don't have any special tools.
                              I assume you have a indicator similar to this
                              https://m.media-amazon.com/images/I/...L._SL1162_.jpg
                              ?
                              You want to do it in the lathe or on the mill !
                              Lets take the mill. Center the quill on your T slot
                              Lay the cylinder on the table ...in the T slot ( It's now centered.
                              Put a indicator in the quill and set it horizontal with prob , then lower it into bore and use Y axis to confirm centering on the ID of the tube
                              stay there and lock quill temporarily while at "0" ! -- Now raise the Quill collar stop ( Not the quill) to hit the moving stop , and then release quill clamp
                              Take a heavy Duty Mill Washer ( like 3/16" thick ) and measure ID and OD so you know width of washer
                              Set it in the groove and move the into the washer by raising the quill slightly and finding "0" again
                              now measure the difference in your quill stop collars and using the washer width , you get depth.
                              For width of groove , turn the last word prob down ward 90 degrees and using X axis , measure deflection point PLUS diameter of prob. for width measurement

                              Rich
                              Green Bay, WI

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