OK Zaxis Zeroing Technique - Benchtops/Mini/Bridgeports!

[bill south]

A question for the home hobbiest. What is the best, easiest, most accurate method or methods, for setting the z-axis to zero. I've read about using feeler gauges, setting it by eye (does not apply to my 54 years young eye balls), or using new fangle electronic gizmoes (there is a new thread on this today, go figure!!!), or maybe tissue paper during a full moon!!! Cost is always a factor but I'm wondering just what everyone is doing!!!
All inputs are appreciated, especially those who have been creative. It always amazes me how some jobs get done!
Bill from South Carolina

[Ron111]

Bill,
I've started cutting strips of paper, and using that as a feeler guage under the cutter. It's repeatable for me, and I think I had seen it in the Tormach manual from their web site. They may have used cigarette paper. I just cut up strips and measure the thickness.

Works for me,
Ron

[bryanrabb]

what about tool setters?

Go cocks!

[S_J_H]

I use paper on top of the work or with a gauge block. Fast and easy.

Steve

[drawbar]

I third the paper trick. Right on top of the work. When the paper just starts to grab under the tool, I set Z to 0.004. That's close enough for me.

Brian

[bill south]

Thanks Guys. I'll have to try the paper trick this weekend. Sounds accurate enough and most definately, my price range!
Bill

[BobWarfield]

The paper trick, often referred to as using cigarette papers (they're thin, uniform in thickness, and were in everyone's pocket at one point), is the most common way to do touch-offs (the official name for this action).

If you need more precision, there are electronic devices (as mentioned) and there are also rigs that use a dial indicator. The latter can be built if you have a spare indicator (there is a nice bit about how to do this on the Industrial Hobbies web site), or you can buy a handy little gadget to do it that is built into a cube exactly 2" high. You move down until the need moves, read of the value, and the offset is exactly 2.<value>". You can set the little cube atop your workpiece or the machine table depending on what sort of offset you're trying to determine.

eBay seller 800watt offers these little cubes on eBay for circa $30. Just do a search on "presetter" under the Business and Industrial category and you'll see a variety of such things. Auction #140026272002 is one such. Just put that auction number in the eBay search to see it.

A related approach is to preset the tooling in the holders at a known height, use the tool offset table in your CNC software, and just tell the program the known height. You can either measure the heights with a height gage, or buy a tooling system from an outfit like Tormach that offers a system designed to keep them all at the same height.

So there's really two issues. One is finding "Work Zero" and one is accounting for different tool lengths. You're CNC software will let you attack these separately (nice if you have multiple tools that want to run quickly for production) or treat it all as one event.

Best,

BW

[dcprecision]

How about building a zero setter using a l.e.d. and disc battery. You could make a 3 layer aluminum block using delrin or a similar materilal to isolate the electrical poles. Once completed, measure it to establish the known height value or adjust it to a desired value. I think it would take less than 2 hrs. and cost less than $4.00 in parts. Plans for a practical device may be a good post topic, any suggestions.

[chich2]

I place a mark on the top of the job with a permanent marker pen and then VERY carefully bring Z into contact with the spinning cutter until I see the cutter scratch the ink....... Very close! Havent had a problem yet. Same procedure for X and Y.

[philbur]

Hi Bob, this is not correct. You still need a height gauge to provide the tool offsets. The point of the Tormach system is that the tool tip always remounts in the same z-axis position, eliminating the need to "touch off"
again.

Regards
Phil

Originally Posted by BobWarfield You can either measure the heights with a height gage, or buy a tooling system from an outfit like Tormach that offers a system designed to keep them all at the same height. BW

[BobWarfield]

Originally Posted by philbur Hi Bob, this is not correct. You still need a height gauge to provide the tool offsets. The point of the Tormach system is that the tool tip always remounts in the same z-axis position, eliminating the need to "touch off" again. Regards Phil

Tormach ships a height gage and small surface plate together with their toolholders. If you have mill holders, a height gage, and a surface plate, what is to keep you from setting them yourself to a fixed height? Yes, you lose their quickchange aspect, but at least all the tools are at the same height, or perhaps one of a very small set of heights easily remembered or labeled on the tool rack.

In fact, you can buy commercial systems that do exactly this called tool pre-setters that are intended for use in the tool crib. When you go check out a tool, it's in the holder and you get a slip of paper telling you what height and tool table entry to select.

So given your own height gage, and a bit of ingenuity, you can duplicate the fixed tool height function of the Tormach system by presetting your tools to a known height with your gage.

Best,

BW

[philbur]

Hi again Bob, We may be passing one another in the doorway here.

If you have a tool holder with an MT or R8 taper what height will you measure, from the tool tip to where? The Tormach system fits spindle shoulder to tool holder shoulder so you measure from tool tip to the tool holder shoulder. It's not a fixed height it's a known height. This gives repeatable height location to a very high degree when used with tool offsets.

Regards
Phil

Originally Posted by BobWarfield Tormach ships a height gage and small surface plate together with their toolholders. If you have mill holders, a height gage, and a surface plate, what is to keep you from setting them yourself to a fixed height? Yes, you lose their quickchange aspect, but at least all the tools are at the same height, or perhaps one of a very small set of heights easily remembered or labeled on the tool rack. In fact, you can buy commercial systems that do exactly this called tool pre-setters that are intended for use in the tool crib. When you go check out a tool, it's in the holder and you get a slip of paper telling you what height and tool table entry to select. So given your own height gage, and a bit of ingenuity, you can duplicate the fixed tool height function of the Tormach system by presetting your tools to a known height with your gage. Best, BW