What Zero Height Setter?

[Jasonb]

Andrew's recent mention of setting tool heights has prompted me to ask what members suggest as a suitable height setter for my CNC.

At the moment I'm just using the 20mm side of a 10-20-40 block and jogging down until they won't slip under the tool but would prefer something a bit better than that. I don't have any quick change tooling so break the program down into sections for each tool, run that then load the next code and change tool.

I don't feel I need one that wires into the machine so just one of the blocks or cylinders with a dial or digital readout, I'm thinking the dial is easier to see what's happening rather than counting down on a digital one. Also as most of my items are quiet small I'd like the setter to be the same so a 50mm height one with a smallish footprint.

Any suggestions?

J

[Vixen]

I made this elephants foot tool height setting dial a while ago. The photo below, should be self expiatory. I find it is useful for measuring the tool offsets for a rack of tools. The individual tool offsets are entered in the tool table. The CNC controller compensates for the individual offsets as each tool change is called and loaded into the quick changer.



For single tool setting, I still prefer to touch off onto a thin strip of typing paper. I jog down in 0.001" (or metric equivalent) steps until the tool just nips the paper. Set zero and lift the tool and your ready to roll.

Mike

[steamer]

I have the Tormach height gage and special granite plate for setting tool heights individually.   Though I think setting it on the machine is a better idea in a small crowded shop

Dave

[steamer]

Having a usb link from the tool setter to the control is nice...eliminates typos.   The Tormach tool setter will do this

[kvom]

I use a 1" gauge block, but only jog upwards until it slips under the tool.

[Admiral_dk]

There are a number off cheap (not always sold at a cheap price) Height Setters out there. They are basically a  simple switch that has a reasonable accurate (not from switch to switch, but from test to test with same switch) point and a good long service life. Most CNC Control programs (LinuxCNC etc.) has an option to connect them together. The program will slowly 'Plunge' the Mill-Bit down until it triggers the switch and then even slower rise it again until the switch is inactive - this point will be the Zero Height !!!
I've seen a few programs do it a few times very shortly after each other - I do not know if it just confirms or do an average to improve the resolution of the switch.

I have discovered a problem with this approach when the diameter of the mill bit increases - you might either not have the lowest point off the mill bit / head be the part the touches the switch or it might press the switch at a slight angle that changes the switch point.

All this can be improved by making the whole system yourself on the lathe. First make a rough 'plate' bigger in diameter than you biggest milling head. Attach a straight precision axle to it - in such a way that it can't go loose !!!
Then hold the axle in the lathe - probably best option would be in a collet - and remove enough from the 'top' to ensure a very flat, smooth and perpendicular surface to the axle. Optimal end result off this part, should be stiff and light - the later can (and probably should) be helped with an assist spring.
Now make a Base with a flat bottom and options for securing it to the mill bed, that has space inside for the switch and two wires out + a straight perpendicular hole for the axle.

I hope this might be useful 

Per

[Hugh Currin]

I do this with a machined 1" piece of aluminum. Will have to pop for a real gauge block one of these days. I generally move the tool too low, jog up 0.005" increments till the block slides under tool, then jog down by 0.001" until I can just slide the block under the tool. This to counter backlash. But, as kvom says, don't jog down while block is under the tool. The machine will use every bit of force it can muster to force the tool that last 0.001" into the block. Bad bad.

I have Tormach quick change tooling and really like it. My set came with a small granite setting stand that I have yet to use.

Will be interested in what you come up with. Thanks.

I use a 1" gauge block, but only jog upwards until it slips under the tool.

[Dave Otto]

I just use a spare .1" gauge block. At work I have a nice 2" spring loaded checker with an LED indicator that works quite nice.
My home machine is a converted knee mill with limited Z travel so any type of height setter takes up precious space.

Dave

[cheepo45]

I use a .001 feeler gauge and a block.
Just move it down until it grabs the feeler, nd add .001 to the block for your Z setting.
 Scott

[Dan Rowe]

I have a pack of rolling papers in top of my machinist box. They measure .001" tear off a strip and hold it lightly and when it grabs set the dial.

Cheers Dan

[Jasonb]

Thanks for all the replies, it seems like what I'm doing already is not a lot different to what the rest of you use so maybe I'll just stick with that.

Vixen's one with the dial looks to be the closest to what I was thinking off but a bit bulky for setting individual tools and Dave's light up one would be a similar shape but I think I would prefer a dial to see how far to jog if I did buy something.

keep the ideas coming.

[Vixen]

There is always these, from China. They come with their own make-up box!!

These setters are 50mm tall. My 'home made' dial setter is currently 32mm tall but could easily be remade to 25mm (or less)

https://www.ebay.co.uk/itm/Z-Axis-Setter-Magnetic-Measuring-Tool-Pre-Setter-50mm-for-CNC-Router-Machine/283250188028?_trkparms=aid%3D1110006%26algo%3DHOMESPLICE.SIM%26ao%3D1%26asc%3D228435%26meid%3D33b8d387ff8440d59ac98a36e88d0fb4%26pid%3D100005%26rk%3D3%26rkt%3D12%26mehot%3Dpf%26sd%3D173528747532%26itm%3D283250188028%26pmt%3D1%26noa%3D0%26pg%3D2047675%26algv%3DSimplAMLv5PairwiseWebWithoutBoostBBEV1&_trksid=p2047675.c100005.m1851

Mike

[Jasonb]

Yes those were the type of thing I had in mind, just wondered if anyone may have used one and if the repeatability was OK.

I've got plenty of height but as I often use the top of the part as my Zero want a smallish base area, yours looks quite large and not that balanced unless on a nice flat surface.

[Muzzer]

Check out Cluff's video on the subject:
<a href="https://www.youtube.com/watch?v=wDGvQHevN9Y" target="_blank">http://www.youtube.com/watch?v=wDGvQHevN9Y</a>

[Jasonb]

Thank's Murray, good video and seems like the dial type is the way to go. I've not seen his videos before so will have a look through them over the weekend.

J