Designer 2.0

[bergerud]

That works for some fractions. You can't enter in 125/128" in fractional OR decimal (0.9765625") form.

And actually, I just tried entering in 1/16", and it outputs .063 as a decimal, not .0625. Maybe I'm not entering it in the correct location?

I think the problem with the long decimals and 125/128 is only a data input and display problem. 1/16 does give 0.0625 as can be witnessed as to how the snap grid fits on a board. 0.063 is different. If I remember, there are like 6000 encoder ticks per inch for y and z. Maybe more for the x. Servo accuracy is not a problem. There may be something to what you say in how the software deals with numbers. Now I am going to have to do some experiments.

[brdad]

I found the quoted information in the FAQs which shows I may be wrong.
Granted, they are talking about raster carving lines and not vectors like a drilled hole, but you'd think the resolution was comparable.
Now I'm even more confused than before. The only thing I can figure is the software only handles 1/128" increments with vectors and other dimensional data, even though the machine is capable of more?

What is the resolution of the machine?
The core capability of the CarveWright is as a carving machine. The machine configuration and control software are quite different than a classic mill. As such, the terms resolution and accuracy are hard to correlate to what you expect from a classic milling machine. Our controllable resolution is .00025″ on the Y and Z-axes and .0015″ on the X-axis. The accuracy of any single raster carving line is on the order of .005″ – .010″ in the Y and Z and the step width is between .005″ and .010″ depending on the quality setting you choose. When you are talking accuracy of position of two elements across a 60″ board the value is even higher.

[bergerud]

Ok, I will do a test. 1/128 = 0.0078... I will drill a 0.496" hole. If you are right, the 0.496" hole should turn out to be either 63/128" = 0.492.." or 64/128" = 0.500".

As an accuracy test, drill a 1/2" hole and see just how close to 1/2" you get. I believe that bit run out is also involved in this. With my ER spindle, my 1/2" holes are such that a 1/2" router bit shank is a light snug fit. Just enough friction to support the weight of the bit. It only takes a slight run out to create a larger hole.

(I suppose this is a subject for a different thread since it may have little to do with Designer 2.0)

[bergerud]

Ok, I drilled a 0.496" hole in some cast acrylic. It came out as 0.4965". I have to say that I do not think there is any rounding to 1/128 ths.

[henry1]

got agree with bergerud being he is a math teacher

[brdad]

Agreed, these posts could be moved to their own topic. Sorry to everyone for straying and sorry to bore anyone not interested...

I made a test cut as well. 24 holes in acrylic - using the 3/16" bit in my Rock Chuck, varying from 0.490" to 0.513" in 0.001" increments. I also made three test holes of 3/16", 1/4", and 3/8" to verify any run-out...

One conclusion I have come to is my holes are not round. On the three test holes, the Y dimension came out within 0.001" of the design size. It seems like run-out should be more than that, but my 3/16" bit may not be exactly 3/16" either.

As far as the other 24 test holes - On the Y axis, my measured hole often comes very close to the designed hole, most of the time even smaller by 2-3 thousandths. But they are not consistent. The lack of the consistency is probably the machine - I don't think we could expect the CW to consistently maintain .001" tolerances. The X axis measurements are all over by 5-7 thousandths, which I might be able to correct with calibration, but no amount of calibration will cure any inconsistency. My 0.5" designed hole came out at X = 0.505" and Y = 0.494"

Incidentally, finding the hole my half inch shaft router bit fits in to - It will drop right into the 0.504" designed hole, and is a tight press fit into the .503" designed hole. The bit measured out at 0.4995", the actual hole sizes were X = 0.506" and Y = 0.499" for the tight-fit hole and X = 0.508" and Y = 0.504" for the loose hole.

In either case, it does look like my 1/128" theory is debunked. But I like finding the truth whether I'm wrong or not. Maybe I should change over to metric where I can't get confused with fractions and the fact Designer can't load more than 3 decimal places!

[bergerud]

Your y data seems pretty good. Run out does not seem to be a problem. Maybe all you need is a little x axis tweaking.

[Digitalwoodshop]

WOW... Thecno Speak at it's best..... to me.... "Humidity and Wood the Sponge trumps .00001."

My brother was a MR2 or Machinist on a Sub Tender in Norfolk in the late 80's. Watching him machine a pump shaft then give it time to cool before making another cut after measuring... Taking into account expansion and contraction...

In my last 4 years in the Navy I did Shipboard Weapons Alignment. We would use Surveyors Transits or Theodolites to measure the Gyros, Radars, Guns and Missiles Roller Paths and install corrections to the software to correct for slight tilt between all the elements. As the Sun came up and started heating the Warm Side of the Ship, we could see the readings move.... Quitting time.... OR as we called the alignment... a "Snap Shot" of the system in time" 30 minutes later the numbers would be different... Now they even measure the Satellite Communication Antennas...

I remember a post in 2007 where a user had a broken X Gear and it came from cutting a board that was sitting edge down on the Cement Floor and had sucked up moisture to the point that it was wider on the end then middle and JAMMED....

AL

[CarverJerry]

If you need an exact size of a hole say like in acrylic then I'd say drill it undersize and use a reamer to hold perfect size, like they do in a machine shop, and as Al said temp is a big factor in exact sizes, weather it's ID (inside diameter) or OD (outside diameter). Just my experience in the 40+ years as a machinist.

[lawrence]

I think the way it works is that it shows .063 in the box but the machine actually records .0635, but I'm sure someone with more knowlege on this will be around to correct me if I'm wrong.

Lawrence