Ryan's 1.0 Build

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Re: My Buildlog.net Build

Postby bdring » Wed Feb 16, 2011 4:30 am

The cover does tend to be a little wiggly. It gets better with the covering. Yours may be extra wiggly with just plastic. If you lift it evenly, it does not matter that much.

You need to be careful when installing the gas springs. They can put a lot of stress on the frame. The gas springs should only be strong enough to hold open the cover. You can adjust by playing with the locations of the ends. Get it all adjusted before you put the tube in. I had a loose bracket and the gas spring started to pop the back off the frame. I had the tube installed and got a little scary.
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Re: My Buildlog.net Build

Postby r691175002 » Sat Feb 19, 2011 8:01 pm

Going to skip ahead here, what would cause retina engrave to work perfectly in raster/jog mode but not do anything in vector mode?

I've only got a multimeter but the dir/pulse pins are working as expected in vector mode, I have a suspicion that the timings are a lot faster in vector mode and the keling drivers aren't picking them up.
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Re: My Buildlog.net Build

Postby macona » Sun Feb 20, 2011 9:43 am

Sound like a software issue.
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Re: My Buildlog.net Build

Postby r691175002 » Thu Feb 24, 2011 3:12 am

Most of the assembly has been already finished. The individual acrylic components are all ready to go and the frame has been assembled so now I've just got to stick em together. Follow the diagrams, it isn't actually that difficult.

I did not have the foresight to include all the necessary nuts on the extrusions. Some disassembly/reassembly was needed to get all the nuts in place. You can also use post-assembly nuts which snap into place. They are more expensive but oh so worth it. I got ten but would do twenty or more if I could go back in time. Of course, if I could go back in time I could also just include the correct number of nuts in the first place.

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A small hole is tapped for a set screw to link both sides of the y-axis. For some reason this is at an angle when tightened which causes the threaded rod to whip at high speeds.
I consider the threaded rod and this linkage the weakest part of the build and suspect that it twists at high speed and does not accurately link both sides of the y-axis. I plan on replacing it with some 1/2" aluminium rod at some unknown point in the future but it works well enough for now.

This pretty much covers the mechanical side of the build. It is hard to estimate the time spent to this point but I'll try. At least 10-15 hours were spent researching the build and ordering parts online. Around 30 hours were spent assembling to this point.

Note that there is still a lot of finishing touches to add. The enclosure, switches, air assist, venting, vacuum table... While the gantry is certainly functional as-is, expect a lot more work to make it professional.
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Re: My Buildlog.net Build

Postby r691175002 » Thu Feb 24, 2011 3:36 am

The table is going to be one of the main modifications I make to the original plan and a fairly major money-sink compared to the bare minimum.

The easiest table would be to slap on some cheap plywood and glue aluminium foil to it to prevent burning. This would be cheap and easy but have the disadvantage of reflecting the beam against the back of the material. In general, this will produce less attractive cuts and may cause problems with certain materials.

The second option is to use perforated sheet metal. Since only about half of the surface is metal you get less reflections and the air assist can blow straight through the material clearing the smoke faster (for cleaner cuts).

The best option is aluminium honeycomb. It has virtually zero solid area. The main problem is that while it isn't particularly expensive, you basically have to buy an entire sheet.
McMaster will sell quarter sheets already expanded for about 100$. The disadvantage here is you are paying enormous amounts to ship it and they have only very coarse grids.

For about the same price I bought an 8' by 4' sheet of 1/2" cell honeycomb from http://www.honeycommcore.com/ . They will cut to the exact thickness you require and give you the option of shipping unexpanded (cheap) or expanded (good luck shipping a 4x8" sheet). Their webpage looks a little sketchy but they were extremely helpful and did a great job. I got them to cut me a slice that is 20mm thick, the exact thickness of the aluminium extrusion so it will lie flush in the table.

I am debating whether or not to build an enclosure under the table to apply suction from below. I suspect that it will not provide a huge advantage since air assist is already blowing downwards. As well, since most of the table is open the chances are that any vacuum created would be extremely minor and might not warrant the extra work.

Here is what the unexpanded sheet looks like:
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It came shipped in a tube and is around 5' long 1" wide.

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Now let me tell you that this stuff is hard to expand by hand. I cut the 5' bar in half because expanding the entire sheet at once would be hell and because I don't need very much. Start by getting a feel for the material and stretching it slightly by hand. It is very springy and slightly sharp. Once you have it open slightly you can put a bunch of nails into two boards of wood and slide the honeycomb over the nails.

Then just grab a buddy and pull. It is pretty hilarious to see 1" stretch into eight feet.

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Here you can see the table I plan on filling as well as the unexpanded half-sheet that remains. You are going to waste a good part of the sheet doing it by hand, but I still have enough for at least 6 tables.

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The aluminium is very thin and you can cut it with scissors one segment at a time. It is hard to get the exact size right so I just said screw it and shoved the corner in. The cell deformations don't look that bad and won't affect anything so I don't consider it an issue.

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The honeycomb isn't super rigid so I will be supporting it from the back with some aluminium angle.

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I tried to save time by using glue. I started with weld-bond which didn't work. I then redid it with goo which fell apart after a few days. I finally did it properly by bolting it together.

Probably took about 7 hours because of the number of times I messed up.
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missing Fold Back Bearing

Postby bdring » Thu Feb 24, 2011 3:56 am

It looks like you are missing a fold back bearing near the motor. The engagement of the pulley might be too light.

It is supposed to look like this...

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Re: My Buildlog.net Build

Postby r691175002 » Thu Mar 10, 2011 2:38 am

There hasn't been any problems with the belt skipping so I haven't bothered to include the extra bearings.

I've gotten most of the electrical side of the build coming together:
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Soldering the motor wires.

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I want the wiring to be somewhat clean so I'm heatshrinking and sleeving everything.

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And testing the motor via mach 3. I didn't have a parallel port on my computer so I ordered a pci card off the internet which worked fine.


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I decided to mount the electronics to an acrylic panel because acrylic was the only material I had on-hand.

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I managed to fit everything in although it was a little tight.

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Starting to look closer to completion.


I also recieved the laser tube. I ordered from love-happy-shopping on ebay and was very pleased. The tube came wrapped in bubble wrap, stuffed into an 8" pvc tube which was then rolled in several meters of foam and bubble wrap. I could imagine the package surviving being thrown out of a plane. To my delight everything worked on the first try which almost never happens.
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Up next, beam alignment, red dot and air assist. I actually had one of our cats rip most of the wiring to shreds which set the project back a fair deal. I kinda expected them to play around but I wasn't expecting actual damage.
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Done!

Postby r691175002 » Mon Apr 11, 2011 10:24 pm

I've been neglecting updates for a while but there isn't really much aside from routine assembly.

I had some trouble with the electronics. The stock Retina Engrave board from FSE outputs some pulses at 1us and some at 5us which wasn't fully compatible with my Keling 4020 drivers.

They were quite helpful and wrote a special firmware version that fixes the problem. Although it took a bit of time to fix, my machine now works very well in both engrave and vector mode.

It seems fitting that my machine makes its own last pieces so here it is cutting out the brackets to mount the gas springs:
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Cut quality is great, 6% speed 100% power (15mA).
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There has been a lot of small things added to the machine and a few more I need to add as well. I've got a reed switch activated by the lid so that the laser goes off and a light goes on when the lid is opened. I have a seperate pic 12f683 running the Z-axis off one of the switches so it is easy to adjust. There is red dot aiming and a 3W led on the carriage so it is easy to line up.

The blue LCD on the lid shows the current running through the tube. By some freak accident of Chinese manufacturing, the display was improperly calibrated and shows 15mA as 10mA. I've set my maximum to 15 (as per FSE recommendation) so if I put tape over the dot it reads 0-100% power which is pretty snazzy.

Currently air assist and the water pump are wired seperately (plugged into the wall). I've got the switches mounted so I just need to wire them up.

The main addition i am waiting on is ventilation. I am going to have to move the machine to its final location (to be decided, but probably downstairs which is going to be awful to move) and I'll wire everything up once I'm there.


All said and done I am quite satisfied with my build. A few pointers to those who are thinking of doing their own:
Use polulu drivers, at 13$ a pop you save a lot of cash over kelings.
Make sure the L-brackets for the extrusions are on really tight. If they are only somewhat tight they can twist/slide.
I am pleased with my decision to use a honeycomb table, when cutting acrylic you can see the smoke shoot through the cut.
If you have a computer with a parallel port, give mach3 or emc2 a shot. It is quite easy to use and can save you a lot of money compared retina engrave or the dsp controller.
Use locktight on all the pulleys. Make sure that setscrew is really really tight.

With what I know now I could probably do a 2.0 build for around 1000$ (this one ended in the 2500$ range).

Although it was more expensive, I am happy with my purchase of Retina Engrave. Once I got the quirks worked out it is very easy - Open literally any program, do some doodles or type some text and press print. The software can arrange the cuts in any combination of power and speed as well as engraving very well.

I saw some hexagons on the internet and figured I could make my own. A few minutes in inkscape and I have a pile to play with:
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Its a great tool to have. Things that would take me hours to do by hand are a few minutes away and are perfectly accurate.

Thats pretty much it.
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Re: My Buildlog.net Build

Postby naPS » Tue Apr 12, 2011 1:40 am

Which version of the polulu drivers did you end up using?
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Re: My Buildlog.net Build

Postby artwood_decor » Tue Apr 12, 2011 1:59 pm

Great build. and I appreciate a lot the high quality detailed pictures.
Could you suggest more tips for saving as you mentioned you would be able to build the machine for $1000 vs. $2500 you actually spent.
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