DRO Functions

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KellyJones
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DRO Functions

Post by KellyJones »

I bought a DRO for my mill a few years back and I am very satisfied with it. It has made my amateur milling attempts much more pleasurable.
I had a thought the other day, as I contemplated how to step up my game in the shop.

Do any DROs provide feed rate information? That would be handy for a novice like me.
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atunguyd
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Re: DRO Functions

Post by atunguyd »

Touch DRO provides federate information.

Actually if you add the tachometer functionality to it and input your tool parameters it can even report the tooth load while you mill

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carlquib
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Re: DRO Functions

Post by carlquib »

My DRO PROS EL700 has this feature. It can be quite handy to know what your feed actually is. I don't know if any of their other displays display the feed rate. Helps to adjust the feed rate to get a precise feed per tooth.

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pete
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Re: DRO Functions

Post by pete »

My Newall does, but if you know your feed screw pitch it's not hard to figure out the number of teeth on the cutting tool, rpm verses the tooth load for each cutting tooth and how far you need to travel per minute to get what your calculated feed rate should be. The dro makes it even easier since you then know the distance required to be moved and can instantly check it against whatever your using as a timer. It takes a bit of trial and error before you have a rough idea of how fast or slow to turn the hand wheels, but that doesn't take long to pick up. You don't even need to be cutting metal to double check your feed rate the first few times.It's probably easier to just observe how the machine is reacting to the depth of cut chosen, feed rate, material type and what your chip size is though. Other than maybe cast iron and some alloys of brass you should always be taking actual chips and not dust. Too slow on the feed rate and the cutting tool will be rubbing and wearing itself out. Ideally the work piece should remain fairly cool since you want most of the frictional heat generated to come out in the chips. Tiny end mills are still going to produce almost dust so the smaller the tool the less you can go by actual chip size.

Just remember the recommended rpm and feed rates in something like Machinery's Handbook are maximums used in industry where time is money. And tool wear isn't linear. A 10% reduction in rpm doesn't necessarily reduce the wear by 10%. It will usually reduce it by a lot more than that. On average I stay away from those maximums and instead try for about 80%-90% of what the book numbers say that maximum is. High speed Steel tools are a lot easier to know what those maximums are than carbide. I've seen numbers quoted for different carbide grades and coatings anywhere from 3-12 times the rpm for HSS. So both the rpm and feed rate numbers can change a lot. With carbide my own personal rule is the chip should come off the part at most as a light tan color, if it turns blue after that your still ok, if it turns blue as it's being formed your rpm is too fast and tool wear will be very high.
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Steggy
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Re: DRO Functions

Post by Steggy »

atunguyd wrote: Sun Oct 11, 2020 3:28 pm Touch DRO provides federate information.

Actually if you add the tachometer functionality to it and input your tool parameters it can even report the tooth load while you mill

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Here, let me fix that for you: :D

Actually if you add the tachometer functionality to it and input your tool parameters it can even guess the tooth load while you mill

There is more to tool load than feed/speed, right?
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John Hasler
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Re: DRO Functions

Post by John Hasler »

If you mean chip load, no. Tool parameters, speed, and feed determine it.


https://cimquest-inc.com/what-is-chip-load/
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Steggy
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Re: DRO Functions

Post by Steggy »

John Hasler wrote: Mon Oct 12, 2020 7:08 amIf you mean chip load, no. Tool parameters, speed, and feed determine it.

https://cimquest-inc.com/what-is-chip-load/
Couldn't open that page. Something about COVID went front-and-center and would not allow access to the content behind it.

I belatedly saw where I copied "tooth load" from the OP. :D I often use the word "bite" as a substitute for "depth-of-cut," so a tooth analogy might fit.

In any case, part of the tool load equation is the nature of the material being cut. A DRO isn't going to know anything about that, unless there is a DRO out there that has that logic built into its software.
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Music isn’t at all difficult.  All you gotta do is play the right notes at the right time!  :D
atunguyd
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Re: DRO Functions

Post by atunguyd »

I apologise for the incorrect terminology.

I meant chip load or feed per tooth, not tool load. As described here:
https://cimquest-inc.com/what-is-chip-load/

So TouchDRO shows that the tooth load as well as the linear feeding speed. Quite nice if you want to try maintain a constant chip load.




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John Hasler
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Re: DRO Functions

Post by John Hasler »

Where can I find that tool load equation?
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Steggy
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Re: DRO Functions

Post by Steggy »

John Hasler wrote: Mon Oct 12, 2020 2:33 pm Where can I find that tool load equation?
I was using "equation" in a rhetorical sense. :)
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