touch plate vs tool length probe

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jkanzaki
Posts: 166
Joined: Sat May 05, 2012 3:00 am

touch plate vs tool length probe

Post by jkanzaki » Tue Feb 20, 2018 9:46 pm

Hey Everyone,

Would anyone mind explaining to me the difference between a tool length probe like this one (The Nomad seems to come with one and have a little spring in it). This is a similar product I found online.
http://www.ebay.ie/itm/Werkzeuglangense ... 2459225796

Vs

https://www.ebay.co.uk/itm/Cnc-Z-Axis-R ... 1c9fe92539

Has anyone used one of these tool length probe similar to the one in the first link? Their build quality seems to be superb, after all, they are MADE IN GERMANY right? haha.

What would be the benefit of using the tool length probe vs a zero touch plate? Aside from the build quality.

Thanks
Shapeoko 1 - dissassemble
Shapeoko 2 - 1 x 1m expansion TinyG, superPid, Dw660, Aluminum extrusion bed, Nema 23, acme, Z axis upgrade, Dual Y
Shapeoko 3 - 0051 Stock Dw611, SuperPid, limit switch, 9mm belt

RobCee
Posts: 587
Joined: Wed Jan 08, 2014 11:33 am
Location: Birmingham, UK

Re: touch plate vs tool length probe

Post by RobCee » Wed Feb 21, 2018 2:48 pm

The difference will be in repeatability and build quality.

Both will function the same way, although I doubt that the cheaper one has a nice spring in it. The spring is important to save the tip of your sharp tools; although many people have success with their un-sprung versions. I find I run my tool into mine far too often, so I like the little extra time I get with my spring to hit the E-Stop!

The other nice feature of a sprung tool length probe is that the probing can be setup to confirm on the lift-off, rather than the touch (if that makes sense). This leads to a more accurate and consistent reading from the probe. The way I use mine is to probe down onto it at a fairly high speed, once it touches I probe up until the contact is lost at a much slower speed. This gives me a very repeatable process.

Having said that, the price differential is fairly extreme.
ShapeOko2 #3400 - Chinese 800W AC Spindle - Stiffened X-Axis - TR10 Z-Axis - Inverted Z Motor - Hall Effect Limits - Drag Chains & Custom Brackets

jkanzaki
Posts: 166
Joined: Sat May 05, 2012 3:00 am

Re: touch plate vs tool length probe

Post by jkanzaki » Thu Feb 22, 2018 3:48 am

Did you build the probe your self? Yes the price is quite extreme.
RobCee wrote:The difference will be in repeatability and build quality.

Both will function the same way, although I doubt that the cheaper one has a nice spring in it. The spring is important to save the tip of your sharp tools; although many people have success with their un-sprung versions. I find I run my tool into mine far too often, so I like the little extra time I get with my spring to hit the E-Stop!

The other nice feature of a sprung tool length probe is that the probing can be setup to confirm on the lift-off, rather than the touch (if that makes sense). This leads to a more accurate and consistent reading from the probe. The way I use mine is to probe down onto it at a fairly high speed, once it touches I probe up until the contact is lost at a much slower speed. This gives me a very repeatable process.

Having said that, the price differential is fairly extreme.
Shapeoko 1 - dissassemble
Shapeoko 2 - 1 x 1m expansion TinyG, superPid, Dw660, Aluminum extrusion bed, Nema 23, acme, Z axis upgrade, Dual Y
Shapeoko 3 - 0051 Stock Dw611, SuperPid, limit switch, 9mm belt

RobCee
Posts: 587
Joined: Wed Jan 08, 2014 11:33 am
Location: Birmingham, UK

Re: touch plate vs tool length probe

Post by RobCee » Thu Feb 22, 2018 8:15 am

Yes, I did build my own probe. It's fairly simple if you have access to a lathe.
ShapeOko2 #3400 - Chinese 800W AC Spindle - Stiffened X-Axis - TR10 Z-Axis - Inverted Z Motor - Hall Effect Limits - Drag Chains & Custom Brackets

aggiedan97
Posts: 2
Joined: Wed Jan 02, 2019 3:41 am

Re: touch plate vs tool length probe

Post by aggiedan97 » Mon Jan 14, 2019 1:28 pm

RobCee wrote:Yes, I did build my own probe. It's fairly simple if you have access to a lathe.
Would you mind sharing your design for your diy probe?

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