Dirks 4x8 CNC Router Build

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Re: Dirks 4x8 CNC Router Build

Postby dirktheeng » Wed Jan 30, 2013 2:39 pm

macona wrote:Find a local shop that has a CNC punch press. They can stamp out a bunch real quick.

If you need a lot you could also have a local shop laser them out of a sheet of steel or 17-4 stainless. It is a magnetic stainless.


This is a really good idea! I have a friend that works for a comercial building company. They punch steel there to make bolt hols in structural steel. They have a bunch of slugs there already that are 3/8" thick. That's a bit thicker than I want but could feasibly work. Alternatively, I may be able to convince him to let us use the press on the weekend to punch out 1/8" 400 series stainless (or 17-4).

I could use my sufrace sander with some really rough paper and very very light passes to flatten them all out and thickness them (not that the uniform thickness is needed in this application.
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Build update 30

Postby dirktheeng » Sat Feb 02, 2013 4:02 pm

All,

Sorry I have not posted much lately. I have been waiting to try and figure out the limit switch stuff with Ahren at CNC router parts and waiting on parts so I haven't been up to a whole lot on the router. However, my bits FINALLY got here and I decided to just move ahead with building a temporary table so I could finish setting up the mill for now. Here's a video showing the runout.

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FIRST CUTS!!! FIRST CUTS!!! FIRST CUTS!!! FIRST CUTS!!!

Postby dirktheeng » Sat Feb 02, 2013 4:05 pm

All,

Today is a very very exciting day (actually last night). I got my first cuts!!!! The actual job I ran wasn't all that exciting, but it works!





I have to say I was truly surprised by how quiet the whole thing is. I think the microphone picks up the higher frequency a bit more than it should because the difference in volume between the DC and the spindle wasn't as noticable. It is so much quieter than any router I have ever worked with before!!!
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Re: Dirks 4x8 CNC Router Build

Postby Greolt » Sun Feb 03, 2013 3:56 am

Always exciting to get those first cuts with a home built CNC.

I notice the acceleration rates are quite slow. You might want to try tuning those up a bit.

When you start doing 3D work you will see what a huge difference acceleration makes to overall performance.

Greolt
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Re: Dirks 4x8 CNC Router Build

Postby dirktheeng » Sun Feb 03, 2013 4:12 am

Greolt wrote:Always exciting to get those first cuts with a home built CNC.

I notice the acceleration rates are quite slow. You might want to try tuning those up a bit.

When you start doing 3D work you will see what a huge difference acceleration makes to overall performance.

Greolt


I'll check into that. I think though that part of the slowness was due to slow z plunge rate in vectric. I'll see how it goes. I am excited to try a 3d carving. Have to get the bits for that first.
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SNAFU with first cuts... working out the kinks

Postby dirktheeng » Sun Feb 03, 2013 4:15 am

All,

Ran into some problems with the primary pully on the motors... set screws came loose.



Got the fix down though... kindof a pain!

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Aligning the Z axis

Postby dirktheeng » Sun Feb 03, 2013 4:36 am

All,

After I got the temporary table bolted down, I started working on aligning the z axis for busines!

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Re: Dirks 4x8 CNC Router Build

Postby Greolt » Sun Feb 03, 2013 4:39 am

dirktheeng wrote: I think though that part of the slowness was due to slow z plunge rate in vectric.


I was referring to the slow ramp up to speed on X and Y. These are not in this case affected by plunge rate.

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Re: Dirks 4x8 CNC Router Build

Postby dirktheeng » Sun Feb 03, 2013 5:26 am

Summary of the build activities for the day. Got my first full table surface run done and made some great progress in the shop.

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Z Axis Alignment Data

Postby dirktheeng » Sun Feb 03, 2013 7:45 pm

All,

As per the video, I promised to post my alignment data. I was really impressed with the CNCRP kit accuracy. With the aide of shims, you could acheave near perfect linearity.

Here is the data:

zAxis alignment tests.jpg
Z Axis alignment


As you can see, there is a very minor amount of twist in the gantry. To correct this, I would have to put a 4.5 thousanths shim on the bottom of the RHS gantry and a 5.5 thousanths shim on the LHS. Once corrected, I can expect that the z axis will be aligned with the X axis to within ~0.8 thousanths 95% of the time. The YZ axis is a bit harder to align. It has to be done by loostening bolts and moving by hand. I got it down to less than 0.0005" per inch of travel. The random error contributes to a 95" confidence interval of about 0.00096".

I ordered a few feeler guages to use as shims and a pair 1x2x3" precision ground blocks to do further testing.

I was not able to tram the head correctly without shims. I could adjust it well wtihin the yz plane, but not the xz. I need to shim the gantry and then see how I need to shim the head mount. I'll get that done soon.

After that, the only thing I have to do is set the limit switches to ensure that the gantry is square and I am ready to cut with really great accuracy!
Attachments
zAxis alignment tests.xlsx
raw excell data
(16.85 KiB) Downloaded 1212 times
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