For the Machinists

[CHI_Tool&Die]

For all the machinists, tool & diemakers, and everyone else - would you recommend telescoping gages or small hole gages for a modern machinist's kit? I typically work on +/- .0002 tolerances so I usually use the Renishaw probe or precision gage pins, but I'm doing more and more work that involves deeper thru holes with +/- .001 tolerances or shallow counterbores that really limit my ability to check with a pin. I know that telescoping gages and small hole gages can cause problems as they are transfer tools, meaning I'm measuring with the gage and then checking with a mic so there are multiple levels for me screwing up the measurement, but I'd be using these for the more open tolerances. I also have been told that to get a good repeating measurement it takes a lot of practice on these gages so it would be pretty cool to learn the skill. Also, the old guys at the shop typically take the .001 increment gage pins too, so I need something I can keep in my box when the shop pins are out.

 

[cvairwerks]

I'd be looking at Mitutoyo 368 Series 3 point Holtest gauges, or similar, for the actual work. Spendy, but accurate. Then I'd find some used ball and telescopic gauges to learn with. Ball and telescopic gauges are only going to be as accurate as your mic or caliper that you reference them to. Takes a lot of practice to be accurate with telescopic gauges. You have to be centered and at the same time, perpendicular to the bore to set them.

 

[CHI_Tool&Die]

I'd be looking at Mitutoyo 368 Series 3 point Holtest gauges, or similar, for the actual work. Spendy, but accurate. Then I'd find some used ball and telescopic gauges to learn with. Ball and telescopic gauges are only going to be as accurate as your mic or caliper that you reference them to. Takes a lot of practice to be accurate with telescopic gauges. You have to be centered and at the same time, perpendicular to the bore to set them.

Thank you! That helps a lot. I’ll keep an eye out for used ones then instead of dropping $200 on a new set.

 

[txvwnut]

Your off on your price by $1800.00 for a new set, and that's a small measurement set. I picked mine up used and spent a little over $600, and I only bought the sizes I knew I needed. I've got a lot of experience using telescopic gauges I can get repeatability of a thou but even then I sometimes end up a thou off for the whole measurement. Hole mics are the way to go for accurate inside measurement in my opinion.

 

[Mgdoug3]

I'm just a hobbyist machinist. To be very accurate with telescoping gauges, one needs a lot of practice. Getting the right feel isn't easy, especially if you want to get to 0.001 tolerance.

 

[X1 Mike]

For all the machinists, tool & diemakers, and everyone else - would you recommend telescoping gages or small hole gages for a modern machinist's kit? I typically work on +/- .0002 tolerances so I usually use the Renishaw probe or precision gage pins, but I'm doing more and more work that involves deeper thru holes with +/- .001 tolerances or shallow counterbores that really limit my ability to check with a pin. I know that telescoping gages and small hole gages can cause problems as they are transfer tools, meaning I'm measuring with the gage and then checking with a mic so there are multiple levels for me screwing up the measurement, but I'd be using these for the more open tolerances. I also have been told that to get a good repeating measurement it takes a lot of practice on these gages so it would be pretty cool to learn the skill. Also, the old guys at the shop typically take the .001 increment gage pins too, so I need something I can keep in my box when the shop pins are out.

If you are used to holding 2 tenths tolerance having a grand is a mile. Small hole gages will be fine.

As the crusty ol ******* I used to work with used to say. "If ya don't know what you're doing get out of the trade."

I'm sure you'll be fine. No need to spend money needlessly. You need small hole and telescoping gauges anyway so you might as well use them until you scrap something because of them before you get spendy.

 

[X1 Mike]

I'm just a hobbyist machinist. To be very accurate with telescoping gauges, one needs a lot of practice. Getting the right feel isn't easy, especially if you want to get to 0.001 tolerance.

No offense but that's why you are a hobby machinist. If a guy came into my shop and said he wasn't comfortable holding that tolerance with telescoping (Not T-Gauges) gauges I'd show him the door.

I'm sure that whatever you do for a living there are procedures that seemed difficult to master that you laugh at how easy they are now so no need to fear the telescoping gauge.

 

[Mgdoug3]

No offense but that's why you are a hobby machinist. If a guy came into my shop and said he wasn't comfortable holding that tolerance with telescoping (Not T-Gauges) gauges I'd show him the door.

I'm sure that whatever you do for a living there are procedures that seemed difficult to master that you laugh at how easy they are now so no need to fear the telescoping gauge.

My point is that if he doesn't have experience with telescoping gauges, he won't hold 0.001" tolerance. Getting the right feel, holding it center and pulling it through is a skill that takes time to learn. If he doesn't have a micrometer and only caliper, he definitely won't hit his mark.

Just because I'm a hobbyist doesn't mean I can't hit my mark or hold a tolerance. I have had companies come to me to make parts and delivered.

 

[X1 Mike]

My point is that if he doesn't have experience with telescoping gauges, he won't hold 0.001" tolerance. Getting the right feel, holding it center and pulling it through is a skill that takes time to learn. If he doesn't have a micrometer and only caliper, he definitely won't hit his mark.

Just because I'm a hobbyist doesn't mean I can't hit my mark or hold a tolerance. I have had companies come to me to make parts and delivered.

He says he is holding 2 tenths tolerance so I'm sure he has a decent set of mics. The point I was making and not trying to offend you, but it seems as I have is that if you are doing it for a living it is important to develop that feel.

 

[Packard V8]

Sunnen, Mitutoyo, Starrett, all have dial bore gauges which are used in deep holes, such as valve guides, but they only promise two tenths.





jack vines

 

[CHI_Tool&Die]

Your off on your price by $1800.00 for a new set, and that's a small measurement set. I picked mine up used and spent a little over $600, and I only bought the sizes I knew I needed. I've got a lot of experience using telescopic gauges I can get repeatability of a thou but even then I sometimes end up a thou off for the whole measurement. Hole mics are the way to go for accurate inside measurement in my opinion.

Yikes! I was looking at a completely different tool. Yeah, those sets are really pricey but they look really nice. I may try to convince the company to invest in some.

If you are used to holding 2 tenths tolerance having a grand is a mile. Small hole gages will be fine.

As the crusty ol ******* I used to work with used to say. "If ya don't know what you're doing get out of the trade."

I'm sure you'll be fine. No need to spend money needlessly. You need small hole and telescoping gauges anyway so you might as well use them until you scrap something because of them before you get spendy.

Awesome. It's really difficult for me because the shop I'm at went from being a tool and die job shop to a more production-like job shop. We still do the machining for the dies, but we aren't putting anything together and we are doing larger runs, say like 15-30 parts instead of 1 or 2. The +/- .0002 pertains to most of my work, but I've been working on more open toleranced jobs and all my tools are geared toward really precise work. I've been trying to expand my skill set, but my shop is young (I think the oldest machinist there is a 42-year-old former die maker while the bulk of us are in our early-to-mid 30s) and not many guys have the knowledge regarding telescoping gages or similar tools. Everything, especially the knowledge, went with the guys as they retired.

My point is that if he doesn't have experience with telescoping gauges, he won't hold 0.001" tolerance. Getting the right feel, holding it center and pulling it through is a skill that takes time to learn. If he doesn't have a micrometer and only caliper, he definitely won't hit his mark.

Just because I'm a hobbyist doesn't mean I can't hit my mark or hold a tolerance. I have had companies come to me to make parts and delivered.

He says he is holding 2 tenths tolerance so I'm sure he has a decent set of mics. The point I was making and not trying to offend you, but it seems as I have is that if you are doing it for a living it is important to develop that feel.

Correct. I have never used telescoping gages so everything will be on a learning curve for me but I really want to add to my skillset. I wasn't sure how accurate telescoping gages could be (I want to use them on inside diameters +/- .001 or greater) hence why I decided to pick your guys' brains. I've been using mics and calipers so I'm good on that end (I have a bunch of mechanical and digital mics from Starrett and Mitutoyo that read into the tenths).

 

[dr_clyde]

Telescoping gages and small bore gages are IMO required for any machinist. Small hole gages are much more user friendly on stuff under 1/2". Telescoping gages take a little practice to use accurately and quickly, but once you get the feel down they're very accurate.

I usually will take the measurement 2 or 3 times and make sure I'm pulling a consistent measurement.

An indicating bore gage is much more accurate, but it requires either gage rings or a setup tool with gage blocks to get it set up. They're also a fair bit more expensive than a set of telescope gages.

 

[cvairwerks]

We used to have to do SPC samples with exact measurements for certain holes. Most of the SPC checks were done with Go-No-GO gauges, but every so often the paperwork required the exact measurements. It ended up being such a problem to teach the driller/assemblers doing the work to correctly use and measure with small hole gauges, that Quality was able to force thru buying 3 surface hole gauges. Sure made things a lot easier for us. Even better was when we went to having to measure countersink diameters, and they simply bought digital gauges for it.

 

[X1 Mike]

Correct. I have never used telescoping gages so everything will be on a learning curve for me but I really want to add to my skillset. I wasn't sure how accurate telescoping gages could be (I want to use them on inside diameters +/- .001 or greater) hence why I decided to pick your guys' brains. I've been using mics and calipers so I'm good on that end (I have a bunch of mechanical and digital mics from Starrett and Mitutoyo that read into the tenths).

Nowadays anything can be learned on YouTube and I suggest this channel for learning anything to do with machining. If you have Suburban tools in your shop, chances are you have a pretty ok shop. I spent 20 years in the business and even though I'm no longer in it I still watch these videos and can learn a trick. It's a shame you don't have more old guys. I used to hate getting told I was a dumb kid every day but after ten years when one of those same old guys that called you a dumb kid came up to you and asked you to grind something for him because you could do it better you damn well knew you earned it.

https://www.youtube.com/c/SuburbanToolInc

 

[dr_clyde]

We used to have to do SPC samples with exact measurements for certain holes. Most of the SPC checks were done with Go-No-GO gauges, but every so often the paperwork required the exact measurements. It ended up being such a problem to teach the driller/assemblers doing the work to correctly use and measure with small hole gauges, that Quality was able to force thru buying 3 surface hole gauges. Sure made things a lot easier for us. Even better was when we went to having to measure countersink diameters, and they simply bought digital gauges for it.

Some people just can't get the feel for fine motor skills like measuring with tools like a telescope gage. Or their brains just aren't wired to understand things the same way a machinist does. Manual machining and measuring takes a fair amount of mechanical aptitude, understanding, practice. Cutters are ran too fast, to much/little feed, wrong geometry, etc.

Some things you have to make "idiot proof". I've noticed a LOT of machining operations tasked to non-machinists don't go so well. Anything requiring "feel" tends not to translate well. Teaching guys how to use simple tools like calipers can be a challenge. Common newbie thing would be to squeeze the calipers harder to make them read what the want instead of what it ACTUALLY is.

Some people's brains work that way, others don't.

 

[X1 Mike]

Some people just can't get the feel for fine motor skills like measuring with tools like a telescope gage. Or their brains just aren't wired to understand things the same way a machinist does. Manual machining and measuring takes a fair amount of mechanical aptitude, understanding, practice. Cutters are ran too fast, to much/little feed, wrong geometry, etc.

Some things you have to make "idiot proof". I've noticed a LOT of machining operations tasked to non-machinists don't go so well. Anything requiring "feel" tends not to translate well. Teaching guys how to use simple tools like calipers can be a challenge. Common newbie thing would be to squeeze the calipers harder to make them read what the want instead of what it ACTUALLY is.

Some people's brains work that way, others don't.

Idiot proof brought us things like go/no-go gauges which are the worst inventions ever.

Don't ever accept that something can't be done. Anything one man can do another can learn. You give me a half an hour and I'll have a rank beginner measuring like a champ with telescoping gauges. Measure a bore of a known dimension and keep measuring it until the reading matches the correct size, soon they will have the correct feel and can measure anything they need. Meanwhile the guy on the other side of the shop with the go/no-go gauge still doesn't know why he did something right after being a "machinist" for 2 years.

 

[MushCreek]

I spent a lot of time running a Moore jig grinder, and we worked to very tight tolerances, sometimes less than .0001. We had a whole wall of Deltronic gage pins, which are in steps of .0001". We all knew how to use telescoping gages as well. I still have a set of Moore tapered leaf gages, which are surprisingly accurate if the hole has a perfect edge, and you have really good eyes. We also used to measure larger holes using an indicator. Let's say you're measuring a 1" hole. Pick up a reference surface and call it zero. Move the machine exactly .500, and reset the indicator so it is exactly zero as you swing it past that reference surface. Move over to your hole, and see if the indicator reads zero in the hole. That checks both size and location of the hole. It's particularly useful measuring inside or outside radii instead of a complete hole. It requires a very accurate and repeatable machine and indicator. It's how we did things before the advent of CNC equipment and wire EDM.

 

[laser3kw]

OP: what do you consider small hole? And, is this for a repeating job or for jobber work where you may be doing a different part every day?

 

[X1 Mike]

I spent a lot of time running a Moore jig grinder, and we worked to very tight tolerances, sometimes less than .0001. We had a whole wall of Deltronic gage pins, which are in steps of .0001". We all knew how to use telescoping gages as well. I still have a set of Moore tapered leaf gages, which are surprisingly accurate if the hole has a perfect edge, and you have really good eyes. We also used to measure larger holes using an indicator. Let's say you're measuring a 1" hole. Pick up a reference surface and call it zero. Move the machine exactly .500, and reset the indicator so it is exactly zero as you swing it past that reference surface. Move over to your hole, and see if the indicator reads zero in the hole. That checks both size and location of the hole. It's particularly useful measuring inside or outside radii instead of a complete hole. It requires a very accurate and repeatable machine and indicator. It's how we did things before the advent of CNC equipment and wire EDM.

And that's the way CNC guys should be trained today. I always believed in learning the manual fundamentals first.
I used to run a Moore Jig Grinder as well. We have a full time operator on it but I was second string. I was surface grinding at the time on a Parker Majestic and when he would go on vacation, I would jig grind for the week.

 

[CHI_Tool&Die]

OP: what do you consider small hole? And, is this for a repeating job or for jobber work where you may be doing a different part every day?

I'm looking at a lot of small repeating jobber work. Something where I'm running five parts but I only need to check the first set of holes. I do the hard milling on a vertical mill so the repeatability once I establish the first part is extremely high.

As far as hole size, it varies but most of the holes I'm looking at are usually between .180-.350" with some .400" sizes on the strippers and such.

 

[CHI_Tool&Die]

I ordered a set of Mitutoyo half-moon-shaped small hole gages. Zoro gave me a coupon so I got the set for under $100. I figure Mits have been quality tools for me and they aren't so expensive that if I struggle with them or don't find them that useful I won't be out much cash. If they do work out and I like them, I'm going to spring for the telescoping gages and maybe a full-ball set of small hole gages. I'm excited to try these out at work!

Thank you guys for all the help! I love that I can come to a place like this and pick your brains.