dieselpilot said:
I've also had that problem - try putting it in slightly skew so that it is "oversize" - lightly tighten and then tip it straight - this will force it back to true - tighten further - remove and measure.
Ken
Measuring bores
- Thread starter Ed T
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I've also had that problem - try putting it in slightly skew so that it is "oversize" - lightly tighten and then tip it straight - this will force it back to true - tighten further - remove and measure.
Ken
compspecial
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Hi doc 1955, I'm so glad you explained about snap gauges as I had no idea what they were 
I think we called them spring bore gauges, but I wonder how they work so well in small bores where the radius on the anvils is larger than the bore's
Tel's plug gauge sounds infallible and simple.I always liked internal micrometers but I don't know how small a sizes they come in.
I think we called them spring bore gauges, but I wonder how they work so well in small bores where the radius on the anvils is larger than the bore'sTel's plug gauge sounds infallible and simple.I always liked internal micrometers but I don't know how small a sizes they come in.
mklotz
Well-Known Member
tel said:
A refinement to Tel's technique is to turn a slight cone on the tip of the gage. As you gradually enlarge the bore, the cone will enter farther and farther giving a visual indication of how close you are to the target diameter.
Ned Ludd said:
Ned,
On the DBG I used we had a rod that was adjusted to an exact length. We then put the assembly in a fixture and dialed the reading to give size (which usually had .001 added as a buffer). From this we got the bore size plus or minus the tenths the bore was in or out. This also showed taper or out of round by comparative measuring.
This was a Sunnen dial bore gage so I don't know if the ebay ones work that way.
Does that make sense? Wouldn't you get an exact size? We worked with 4.000 bores and larger so this may not apply for smaller bores.
No argument, just trying to understand before I buy a set.
Thanks,
Sean
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When I setup my Dial bore gauge, I put my micrometer in a vise with rubber jaws. I set the mic to the desired size or close to whatever I think the bore is. Then I zero the indicator on the bore gauge once I get it to the smallest read measurement, I check it twice before I check the bore.
I have sizes between .24" up to 6". It takes four "Stems" to get this range.
I got all these and a .0001" dial indicator for about $130 give or take.
Kel
I have sizes between .24" up to 6". It takes four "Stems" to get this range.
I got all these and a .0001" dial indicator for about $130 give or take.
Kel
doc1955
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Where I work we use to have a set of (not sure what they are called) hole gauges. They where flat about .030 thick and on the side it had the hole size. You would put them in the hole and read the mark on the side to see what the hole size was they were tapered and each gauge covered about a .05 range. No one ever used them because if you had a bur or any type of edge break on the hole you would not get a true reading.
Anyway I just want to say I would not be without my snap gauges. Dial bore gauges are nice but to me to get that little extra accuracy is a lot of hassle and most of the time .0005 is sufficient. I do agree it is nice to have a dial bore in the shop for those cases you do need to get it right on.
Anyway I just want to say I would not be without my snap gauges. Dial bore gauges are nice but to me to get that little extra accuracy is a lot of hassle and most of the time .0005 is sufficient. I do agree it is nice to have a dial bore in the shop for those cases you do need to get it right on.
Thanks for all the replys and keep them coming. I figured that there would be a bit of discussion on this topic. I have some telescoping bore gauges and always felt them difficult to use due to the "feel" issue. I guess if one used them every day it would be different. Also seem a dicey for checking roundness. The very slightly conical "stick" will, theoretically, only touch the bore in a few places and so is also not so good for roundness. To carry it to an extreme, I can imagine it stuck in a square hole giving the OK. The bore gauge seems like a reasonable solution, but does have some limitations as do most methods. I have, in a past life, used air gaging and the system on SUNNEN machines but, as I recall, they both required calibration to "zero" things before you started. Down in the tenths range, temperature starts to be a real issue. A 1" cube of aluminum gets about 1.25 tenths larger in just 10 F increase in temp. This is easy to do just from holding the part. How long do you wait for stuff to cool before you measure. Is the apparent taper due to the fact that one end of the part is colder or hotter than the other etc, etc. Anyone ever tried ball sizing bores? Seems like it could work to make things round and sized at least for those sizes where you can get a nice ball bearing to do the work.
Thanks again for all the feedback!!
Thanks again for all the feedback!!
