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 Plotter to vinyl cutter 
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Joined: Sun Aug 26, 2012 2:08 pm
Posts: 1041
Location: Lacey, WA USA
We have a Houston Instruments DMP-50 pen plotter recently donated, which is an old roll or sheet pen plotter than takes up to 36 inch wide paper. Serial port, I think.

I think we could find a vinyl cutter swivel knife holder that would fit this, or the plotter or the knife holder modded to fit. This could be great for printing out full size templates, blueprint style plans, and for cutting out sign vinyl to make our own sighs and banners. Aftermarket vinyl cutter blade holders are on eBay for very cheap prices now, under $20 will get a holder with a lot of extra blades.

http://www.ebay.com/sch/i.html?_odkw=vinyl+cutter&_osacat=0&_from=R40&_trksid=p2045573.m570.l1313.TR1.TRC0.A0.H0.Xvinyl+cutter+blade+holder.TRS0&_nkw=vinyl+cutter+blade+holder&_sacat=0

Roland seems to be the most widely available, then second is Graphtec.

Then there is the issue of swivel offset compensation. Without swivel compensation, corners will be rounded and ends of cuts won't quite meet up. Please do not confuse this with cutter offset in CNC and G-code, which is a fixed outer or inner offset. With a swivel knife, the blade must drag slightly behind the centerline so that it will swivel to line up with the direction of travel. That means if you simply move the cutter in a square, the corners will be rounded off. So the centerline must go past the corner point by the offset of the tip, then smoothly move back into line with the direction of travel after the corner.

Image

The old Graphtec I have (had, it doesn't work any more) uses a small triangle in a square to test offset cut compensation. Corners should be sharp and weed cleanly.

Image

Some cutters have compensation in firmware, some in the driver, some rely on commercial sign cutting software to accomplish this. I think we can agree that free is good, open source and free is better. It looks like Inkscape has an extension called InkCut for offset cut compensation now, but it may only work with HPGL output for HP plotters.

https://www.timewasters-place.com/inkscape-and-plotters-the-3rd/

Inkscape is free and open source for Windows, MacOS, and Linux:
https://inkscape.org/en/

InkCut:
https://inkscape.org/en/news/2011/03/16/meet-inkcut-vinyl-cutter-and-vectors-plotter/

Drat, it only outputs HPGL and only works in Ubuntu Linux, and Houston Instruments is not on the list of supported plotters:
http://inkcut.sourceforge.net/

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Steve Greenfield AE7HD


Sun Mar 19, 2017 4:27 pm
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Joined: Sun Aug 26, 2012 2:08 pm
Posts: 1041
Location: Lacey, WA USA
Adam McCombs sent this to the mailing list:

Quote:
Ok, so I actually have one of these units. There is software out there that can run this thing, it is built into inkscape and is found under the "plot" export functionality. The language these things talk in is DMPL, which is rs-232 based, the only problem is that the cable has a different pin out. The DMP 50 is one of the better candidates for conversation to a vinal cutter, the pen holder can have a larger spring installed to get the downforce required for vinal cutting, not something that most plotters can have happene. Unfortunately, my HI-50s eprom died before I could start cutting vinal with it, so now I have a HP-7586b 48" pen plotter, that unfortunately does not have enough down force to cut vinal.

If you want more info on the software to run the thing, check out https://www.timewasters-place.com/inksc ... s-the-2nd/ . This is the guy who wrote the plugin. Also, I can't find the website that has the proper pin out for the cable right now, but I did find it on the net last time, and I will check if I can find my manual, which has the pin out in it.

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Steve Greenfield AE7HD


Sun Mar 19, 2017 9:58 pm
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Joined: Sun Aug 26, 2012 2:08 pm
Posts: 1041
Location: Lacey, WA USA
I installed the latest version of Inkscape. Under Extensions, Export, Plot. Then it can be changed to DMPL.

This gets me to wondering how difficult would it be to write a GRBL type of program for the Arduino that can parse HPGL rather than G-Code.

A couple of references for HPGL:

http://www.isoplotec.co.jp/HPGL/eHPGL.htm

https://ohthehugemanatee.net/2011/07/gpgl-reference-courtesy-of-graphtec/

I think that is what this person has done:
http://www.spydy.ch/Doku%20Pen%20Plotter.html

His video:
https://www.youtube.com/watch?v=WJjGzO30D3E

HPGL (Hewlett Packard Graphic Language) is kind of the standard for driving plotters. Since Inkscape can do swivel knife compensation and can output as HPGL, it would be great to have an Arduino with an HPGL interpreter just as GRBL is a G-Code interpreter.

Although it would be even better if Inkscape could also export as G-Code with the same extension that allows compensation.

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Steve Greenfield AE7HD


Tue Mar 21, 2017 11:51 am
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Joined: Sun Aug 26, 2012 2:08 pm
Posts: 1041
Location: Lacey, WA USA
Phew. Hard to find info on this plotter.

Some report they've made simple adapters to fit the Roland blade holders into Houston Instruments plotters. Roland compatible holders on on eBay for $20 or less with a lot of blades.

I've attached the drivers as I'm worried they may go away at any time.


Attachments:
File comment: Houston Instruments driver for all their plotters, Windows 98 but reported to work in Windows 7. Zip file.
HI-MD967-Win98.zip [316.67 KiB]
Downloaded 19 times

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Steve Greenfield AE7HD
Tue Mar 21, 2017 7:39 pm
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Joined: Sun Aug 26, 2012 2:08 pm
Posts: 1041
Location: Lacey, WA USA
I have a Roland compatible blade holder and some 45 and 60 degree blades on the way from eBay. I chose a solid aluminum model.

http://www.ebay.com/itm/181917427770

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Steve Greenfield AE7HD


Wed Mar 22, 2017 2:41 pm
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