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lenord
08-21-2006, 02:01 PM
All,

I am having to bore out a lot of 6" OD x 3" thick Al. rounds with a 1.499" hole. Generally I use a center, 1/2" bit, 1" bit, and then use the boring head in the tailstock or a boring bar with the power feed.
I currently have a set of manual bore gauges and am quite sick of the things. Will the $99.00 Fowler bore gauge be the needed improvement or should I get something else ?
Anyone have an opinion about this ?
Is the electronic version even better ?
There are some other cheapies on Flea Bay too........

Thanks
Lenord

Rustybolt
08-21-2006, 02:10 PM
How many of these things do you have to make? What are the tolerances?It may just be easier to make some over/under plug gauges.

JCHannum
08-21-2006, 02:26 PM
Bore gages like the Fowler are primarily for inspection, and comparative measurements. They have a limited measuring range. The 0.0005" will have a range of about +- 0.025".

An internal micrometer like a B&S Intrimik or a Mitutoyo Holtest might be better. They have a range of around 1.400"-1.600" or 1.200"-1.600" depending on manufacturer. Be prepared to spend $500-$600 for the privelege of owning a new one.

YankeeMetallic
08-21-2006, 02:36 PM
All,

I am having to bore out a lot of 6" OD x 3" thick Al. rounds with a 1.499" hole....Will the $99.00 Fowler bore gauge be the needed improvement or should I get something else ? Anyone have an opinion about this ?
Is the electronic version even better ?

The Fowler manual bore gauges are not that accurate, so even adding the digital head to it won't help the accuracy of the rest of the part.
I'm with Rusty B-
Depending on what your tolerances are, make an over & under gauge out of stainless, or think of what you have lying in the drawers or shelves that are already at that diameter. Do you have a 1.5" endmill? Their shafts are slightly undersized and they would be hard enough not to wear fit after fit.
Maybe a telescoping gauge that is attached to a depth gauge base to square it up parallel with the sides might work.

lenord
08-21-2006, 07:04 PM
The sizes vary. Sometimes the shaft these go onto is 1.503", sometimes they are 1.497". The fit has to be "push on by hand, hard, with no wobbles". It's very hard to get them just right.

I looked for internal mic's, some are a couple hundred. I might try them. I saw some on flea bay that had 3 faces, $400-$700 a set !

In addition to looking for a decent use/on sale internal mic, I think I'll make some over/under gauges out of steel to be sure of what the hole size is/what my bored hole will fit onto.

Thanks for letting me know that the DBG's are not all that accurate. Saved me some loot.

Lenord

LES A W HARRIS
08-22-2006, 07:07 PM
lenord,
a set of three pins, use the .626" - .750" dia set, use the program PLUG from MKLOTZ, he is a member of this board, download from:
http://www.myvirtualnetwork.com/mklotz/
this will print out a text file PLUG.OUT, more options than you can use.
Set range at .6259" -.7499" .001" steps, (half the tol of the -.0002" Plugs)
0.05" difference in plug sizes, set your nominal dia and bingo.

mklotz
08-22-2006, 07:33 PM
PLUG generates its 'available' plug gages from an input minimum, maximum and
increment. The associated text file mentions that, if you have a collection of
pins that do not fit this description, the program can be expanded to read a
data file of available plug gages.

That improvement in the program has already been made for another user but I've
never bothered to put it up on the page. If you need it, contact me via email.