Working On A Drag Knife for Vinyl! #117 - Bassett, VA

[pblackburn]

A limit switch is the safety to save the machine from unnecessary forces created by mistakes. It allows the software to protect the machine from destroying itself. Hard stops are for the extreme failure where software will not prevail. On larger machines, the forces are tremendous. Even a large cast iron beast will bend with enough crashes. With those machines, the thermals or overload protection build into the drives will stop the machine. Limits are a good thing. The Mechmate design in itself is strong but the forces are enough to cause problems. You should hook up your limits in my honest opinion.

[KenC]

Pete, hence I said for safety compliance...
I'm still too lazy to hook them limit switches up...
Maybe I'll have them in my upcoming Plasma table which is using LinuxCNC with MESA 5i25 + 7i76 cards. Apart from 5 channel step/dir ports & encoders, it has 32 i/o pins... must find something to fill the voids...

[Tom Ayres]

How about a limit switch or 2...lol

[KenC]

4 limit switches with dedicated pin each

[Tom Ayres]

Alright, today played with Aspire...starting to get a feel for this stuff... I'm likin' it!

[Tom Ayres]

Surfaced my spoil board tonight and found out the hard way, that dust collection is most imparative. Dust everywhere, entire shop, lots to clean up in the morning I need the hose and to devise an overhead track system. Did get a roll-around computer enclosure (its yellow and big) not sure if I'll paint it and use or sell it (too big maybe) I just don't have the space, heck I didn't have the space for the MM but there it is, all 7' X 14' of it.

[pblackburn]

Dust collection is very important. Get it.

[KenC]

LOL! Can I say "Told you so"
At least tie a shop vac to it for now.

[Tom Ayres]

I just didn't realize how fast it was producing it, I had to use a shop broom to get it off the table and shop fans trying to blow it outside but only managed blowing dust in a whirl wind. Yep, it was like a scene out of a comedy. I've cut several parts that didn't produce anything like surfacing did, I couldn't keep up with it and I was only running at 400ipm (next is 800ipm and a lighter pass at 0.025"). Now I can adjust the z perpendicular to the table and run it again. Ken I can see it now, the shop vac being dragged back and forth accross the table, lol.

[lonestaral]

Welcome to Dust City, population unknown.
I hope to move soon, possibly to Cleanairsville.

[Tom Ayres]

Population...that's been well covered before. 3" deep.

I'm digging out a hose this morning and make a really rough dust shoe by hand until I can find one I like. Are there dxf's of shoes on the forum I wonder...

Oh well, time to get back out there.

[darren salyer]

Yes there are, Tom...
I based my dust foot on the DXF in post 25 of this thread, originally designed by Marc Shales.
I modded it to have interchangeable strip brush holders.
With three lengths of strip brushes to choose from, based on bit length and material, it works pretty good.
http://mechmate.com/forums/showthread.php?t=526

[Tom Ayres]

A side note...A friend gave my son a violin that was given to him by a family friend when he was 9 or so (40+ years ago). The violin was acquired back in Cremona Italy in 1945 after the war and kept to later pass on to someone else (my friend). In 1974 the violin was refinished (Bad, I know) by a hack luthier and is in pretty bad shape now. Turns out it was made in 1673 by a guy that was taught at the same school 20 some odd years prior to Stradivarius. Apparently because there are no Strads left to be had, collectors are looking for violins made by makers of the same school before and after Strad. We don't know it was a copy or not, but because we know the recent history before anyone was looking for this maker's work its most likely not a copy.

The cool factor: In recent years (2006) a violin by this particular luthier sold for 97,000 euros (but was in great condition).

The not so cool factor: Our little find is going to cost $30k in restoration and certification.

It will sit on the shelf until my son gets through college, priorities you know.

[Tom Ayres]

Thanks Darren, I'll take a look see

[IMMark]

Originally Posted by Tom Ayres

A side note...A friend gave my son a violin that was given to him by a family friend when he was 9 or so (40+ years ago). The violin was acquired back in Cremona Italy in 1945 after the war and kept to later pass on to someone else (my friend). In 1974 the violin was refinished (Bad, I know) by a hack luthier and is in pretty bad shape now. Turns out it was made in 1673 by a guy that was taught at the same school 20 some odd years prior to Stradivarius. Apparently because there are no Strads left to be had, collectors are looking for violins made by makers of the same school before and after Strad. We don't know it was a copy or not, but because we know the recent history before anyone was looking for this maker's work its most likely not a copy.

The cool factor: In recent years (2006) a violin by this particular luthier sold for 97,000 euros (but was in great condition).

The not so cool factor: Our little find is going to cost $30k in restoration and certification.

It will sit on the shelf until my son gets through college, priorities you know.

Nice story Tom...sounds like that violin could put your son through college!
Mark

[Tom Ayres]

No, only a swift kick in the arse and a firm hand will get a teen motivated. lol Yeah, it'd be nice to pay for college but Julian has been playing violin for 12 of his 16 years and is exceptional, I'm thinking graduation present.

[IMMark]

LOL...yeah, sounds like you have a family heirloom for generations to come!
Wonder if anyone has made a violin with a MM?
Mark

[pblackburn]

Tom,

Managing dust can be frustrating. Get something on the table now that you can build upon. Never stop improving.

A few tips I learned...

Learn from other professions, like managing drywall dust. Mist the air with water from a spray bottle. The water droplets capture the fine dust, start the decaying process and drop it to the ground. Do it before you sweep, after you sweep and then mop. Mop often to manage the dust.

The dust shoe has to be large enough to allow the super high speed particles to stay within the dust shoe and not be pushed threw the brush.

Balance the draft throw the shoe, you need air velocity to allow the dust to convey. Totally enclosing around the spindle to the spoilboard with the dustshoe slows the air velocity and dust particles will escape but too much opening and the same will happen.

This ties to the previous. Manage the exposed openings under the dust shoe, add a removable leaf to the table so the shoe will not be hanging over the front or back edge of the table if it does so. Close in the sides of the spoilboard so it does not happen there as well.

Use at least a 6" main duct and flex and reduce only right before the dust shoe. Use a minimum 2hp high quality dust collector if that is all you can afford. Pentz recommends 5hp for a small shop. I used less but it is only tied to the Mechmate and I plan to upgrade later.

Old style aluminum tinsel (not the new plastic crap) works well when wrapped around the main trunk to control static electricity if you use S&D 2729. If you don't have any, fold up aluminum foil into 2" width strips and spiral wrap it around the pipe and tie it to ground.

Build a Pentz cyclone when funds are available. It is easier than building a Mechmate and works with amazing results. No dust makes it to the filters.

Rule of thumb, If you can smell it, the dust particulates are in the air. The particulate has to be carried through the air and land in your nasal passages in order for you to smell it. Since I upgrade to the Pentz design, I do not smell the wood anymore when it is cutting.

I hope this helps. In order to not pollute the thread, PM me if you have a lot of questions?

[Tom Ayres]

I'm sure there have been. I know I would like to make atleast one on the MM. The wood for a violin is so costly, the last one I made 10 years ago, the sitka spruce blank (had 60-65 growth rings/inch) 5"w x 14.25"L x 1"t was $186 (it came with certification and serial numbers) and the grade 6a maple back was in the same ballpark price for similar size. You definitely don't want to experiment with that kind of cost involved. These things are best left to touch and feel and mostly to sound they produce. As you know each piece of wood is different.

[Tom Ayres]

Pete, I definitely intend to build a Bill Pentz cyclone when I can find several things, time, money and completion of some of my metalworking pursuits. Could wrapping a bare wire around the pipe then connect to earth ground be efficient enough?

[pblackburn]

Copper is preferred and aluminum second.

[KenC]

For discharging static. I use a cheap 1mm solid core hook-up wire with PVC insulating wire to coil spaciously around the pipe & duct . a roll of 20m is less than 10USD.

[Alan_c]

Kobus had a go at doing a violin: http://www.mechmate.com/forums/showt...postcount=1274

[darren salyer]

I missed that the first time it was posted. Thanks for the link, Alan.

[Tom Ayres]

Cool, looks like he enjoyed that part of it anyway.

[Alan_c]

You will have to chase him up to see if he ever got it finished, I know he has been spending much time riding around the countryside on his bike lately, so not sure how much CNC work he has done recently (maybe his cage needs rattling)

[Fox]

Hey Dino,

http://www.instructables.com/id/Coil...-CNC-Plotting/

[Tom Ayres]

Yesterday I cut my first set of aluminum belt reduction plates (copied, can't think who's at the moment, all the credit to him) for the Z. Busted 3 bits (small ones), learned the feed rates real quick . I used 3/8" X 6" flat bar, was just the right width and cheaper than buying a sheet or having someone laser cut them, plus I got the added bonus of doing it myself.

The cut quality is lacking but we know this when using direct drive, thus the need for belt reduction. I didn't cut quite deep enough (0.003" shy, didn't measure the AL before hand) and left a small ridge at the bottom, but I can easily file that off. I'll attempt cutting the X-Y plates sometime today. Can't wait to get the belts on, hope I've got the right lenght, I'll see, otherwise I'll order some.

[darren salyer]

That's pretty sexy, Tom.
Are you planning to bolt together with spacers?

[Tom Ayres]

Yep, I have some leftover aluminum tube thats just about right. I'll post a few more pics after I get one together.

One more important thing, have a good hold-down system