Simple BLDC controller

[Arlo1]

Hi Jeremy,

Making your design work for high amp situations is much welcomed. Maybe bikes don't handle more than 10kW well, but motorcycles do! I still hope your design will be able to drive the Mars motor I'm using for my Cagiva conversion. This motor is 10kW cont, 30kW for a minute... I'd be more then happy to test!!

Alex

I have multiple plans for some hi hi power aplications!!! So you wont be the only one to test it at hi power levels.
I have a YSR (small motorcycle ) project first then a dune buggy then rear wheels of my daily driven car and some motocross bikes ect. ect.!!! The next ten years of my life will be lerning about how to handle plasma explosions im sure!!!

 

[texaspyro]

The next ten years of my life will be lerning about how to handle plasma explosions im sure!!!

Nahhh, don't worry about it... the first good one will put you six feet under...

 

[liveforphysics]

Ok.

So far, I've gone through a stack of PCB's, and encountered about every stupid problem I can run into. lol (made a crooked jig, didn't realize my wooden platform was warped, non-square cut PCBs, and managed to break a half-dozen bits just from stupid errors.)
For starters, my 60deg PCB cutting bits (which I bought a 20 pack of) seem to have vanished off the face of the earth. That got me off to a bad start. lol
So... I decided to try the best I could with the micro-mills I had, which had a shallow face around 30deg, which made the width not work out. When I ran them at a more shallow depth, it would make the these super fine tracks that made these little hair-fine lines through the copper.

I need to find the damn package of PCB cutting bits.


But, I made a little video and took a picture of the state-of-failure that I'm at right now. I think Thud's code is perfect though, it's just my setup and tooling and nOob struggles that are wrecking it right now.

But, I'm learning a lot, and I will get this figured out right, and the code only takes about 10mins to cut a board, and it seems like the machine cuts even cleaner at higher speed (but again, this is not with the correct cutter, so who knows when I use a PCB bit).

Either way, it's a start, and with the right jig and my nOob-ass figuring out how to setup the machine correctly, we will be able to turn out batches of these things.

[youtube]l4x3A6bHpyA[/youtube]

 

[nieles]

i can write a simple code for you. a few small squares for instance. for setting up the machine..

that way you wont lose so much pcb material

 

[Burtie]

Being able to mill your own pcbs like that looks extreeeeeeemely cool 8)
I hope you get those niggles sorted soon man.

Burtie.

 

[liveforphysics]

i can write a simple code for you. a few small squares for instance. for setting up the machine..

that way you wont lose so much pcb material

That would be great. A code that will cut a jig for me that a locates a 4"x6" PCB would also be great, just a rectangle I can cut in a chunk of aluminum or delrin or something that can bolt to my CNC table, and make it so I can easily insert and locate PCB's when I need to swap them.

It also seems to make a REALLY clean cut on the PCB when I move the bit through it fast, but when the code is moving slowly, it looks like it kinda mashes things around a little and makes a ragged edge. Anyone with CNC experience have any thoughts on that?

 

[liveforphysics]

Being able to mill your own pcbs like that looks extreeeeeeemely cool 8)
I hope you get those niggles sorted soon man.

Burtie.

Yeah, it drills the holes so neat and tidy too. That was always a tedious part I hated about making a PCB the hard way.

I'm thinking to do this the right way, I should put some home position sensors on my machine, and bolt a fixture on there, so anytime I want to do a custom PCB, I just throw it in the fixture, press home, and it starts from the right place without spending 5mins measuring and moving and still getting depth etc off by a bit.

And Burtie, you know anytime you have a PCB you want made, you only gotta send me the code and a batch will show up in your mailbox. Same for anyone doing open-source designs of things that will help the electric-revolution advance. I just gotta get my machining skills up to snuff

 

[bigmoose]

Luke, one tip with respect to depth. I have been able to see an LPKF commercial protoype PCB router machine in action in a lab. To control depth, it has a spring loaded Z axis in the up or out direction. To plunge into the board that machine energizes a solenoid. The Z axis has a very small hydraulic dashpot to control plunge velocity in order to not break drills. The most important fact is that the Z axis has a "foot" that rides on the pcb to accurately keep the Z axis a prescribed distance off the PCB. (The solenoid provides the down force.) There is a collar with fine thread (perhaps 40 threads per inch) to micro tune the depth. (It moves the "foot" up or down relative to the end of the tool.) I have seen some pretty warped PCB sheets routed on that machine. They are indexed with two steel dowel pins, and the sheet is held down with only masking tape!

The guys that run it say they can get 0.008 to 0.010 inch width traces with experience. The machine is reasonably robust, but it takes a skilled technician to constantly turn out quality PCB's. The Model is a 92HS I think. For the 30 degree V router, I think the spindle spins at 30,000 RPM. The tech told me that the high spindle speed is necessary to get life out of the carbide bits.

Also all their tools have plastic collars that are pushed onto a prescribed depth from the end of the tool so that when they are removed/reinserted into the collet chuck, they are at the same depth to a 0.001 or so.

Hope this helps some.

 

[oldpiper]

Luke, what machine are you using for your CNC work?

Thanks,

Cameron

 

[liveforphysics]

A DIY unit made by a member of this board that fit my budget. The machine seems to be capable of amazing work, but a machine is only as good as the user, and this user is sorely lacking skills. But unlike before, I actually have time to tinker now, so those skills will come.

Luke, what machine are you using for your CNC work?

Thanks,

Cameron

 

[Thud]

Here you go Luke:
http://www.2linc.com/engraving_depth_controlling_system.htm
this will solve some tricky leveling operations...
I used a tool dia. .015" this will giv 100% of the copper traces that Jeremy drew...much more than that & you will be cutting into adjacent copper on the thinner areas.

 

[texaspyro]

When you get it all sorted out, I want to suck your brain dry of the knowledge... I bought Todd's mill, then turned around a got an even bigger closed loop one. Milling PCBs is one of the first things that I want to do.

You might want to try making a vacuum holddown plate for the PCB's. They can do a good job of handling warped boards.

 

[liveforphysics]

Thank you for the link Thud. I might get one of those, but I saw proof last night that I CAN do a perfect board with my machine setup, it's just a matter of getting all the different setup things correct on the same pass, and I will be set. I will figure out the right setup, and we will be set.

It's strange how a little thing like tool height, something that doesn't seem like a challenge at all, can be such a PITA.





Texaspyro- I'm thinking the same thing. The jig/fixture will be a block of aluminum with a star-burst pattern of channels in the bottom underneath where the PCB sits, a hole drilled part way down in the middle at the center of the start burst, then an intersecting hole drilled into the side, with a nipple threaded into it that will connect up to a high-volume vacuum pump that I've got. Should make for some solid securing force, and warped board straightening force.

 

[texaspyro]

This place looks like they may have a good start for a vacuum plate for cheap: http://www.veneersupplies.com/categories/Vacuum__Press__Items/Vacuum__Clamping/

A chunk of HDPE with fittings, etc for cheap. I was thinking along the lines of an air hockey table in reverse. Cavity milled out of the bottom, sealing plate on the bottom, lots of small holes on the top, suckage out the side.

 

[amberwolf]

Or just go to some place that does countertops; they almost always have a pile of broken crap they screwed up cutting or gluing that they'd either sell you cheap or give you so they don't have to pay to have it hauled off. It's usually about 1/2" to 1" thick plastic (dunno what type, but it doesn't flex).

At one time I'd planned a vacuform bed out of this stuff, but never got around to it (and no longer have the pieces I'd saved, back in the 90s). I was going to take two large 1/2" pieces, epoxy an edge-sandwich around the perimeter, so they'd be a single hollow piece. Add small blocks about 1/4" wide (but still 1/2" high) every 6" or so to add rigidity to the full surface, so even with really heavy source molds I wouldn't risk cracking it if I were to be clumsy and drop it on there.

Then bore a hole in one end for a shop vac hose and a smaller hole at the other end for a compressor air fitting (to use the compressor tank as a vacuum source, compressor hooked to it in reverse). Then drill 1/32" holes in a grid every 1/2" over one of the large flat surfaces, leaving the other solid, and it'd be a good bed to work with many different types of vacuform.

You wouldn't need the compressor tank for the instantaneous major vacuum source, just a regular shopvac for the continuous one, to hold down the PCBs (or anything else). Then just cover the rest of the holes not in use with glossy paper like junkmail or magazine pages.

 

[texaspyro]

If you just carve out a cavity, the air pressure can bow the top in when you draw a vacuum. To keep the vacuum from flexing the top of the material, you want to mill a channel/channels in the base and have the vacuum holes fed by this plenum. With the channel, you have a lot of support for the top of the plate.

 

[Jeremy Harris]

Or just go to some place that does countertops; they almost always have a pile of broken crap they screwed up cutting or gluing that they'd either sell you cheap or give you so they don't have to pay to have it hauled off. It's usually about 1/2" to 1" thick plastic (dunno what type, but it doesn't flex).

At one time I'd planned a vacuform bed out of this stuff, but never got around to it (and no longer have the pieces I'd saved, back in the 90s). I was going to take two large 1/2" pieces, epoxy an edge-sandwich around the perimeter, so they'd be a single hollow piece. Add small blocks about 1/4" wide (but still 1/2" high) every 6" or so to add rigidity to the full surface, so even with really heavy source molds I wouldn't risk cracking it if I were to be clumsy and drop it on there.

Then bore a hole in one end for a shop vac hose and a smaller hole at the other end for a compressor air fitting (to use the compressor tank as a vacuum source, compressor hooked to it in reverse). Then drill 1/32" holes in a grid every 1/2" over one of the large flat surfaces, leaving the other solid, and it'd be a good bed to work with many different types of vacuform.

You wouldn't need the compressor tank for the instantaneous major vacuum source, just a regular shopvac for the continuous one, to hold down the PCBs (or anything else). Then just cover the rest of the holes not in use with glossy paper like junkmail or magazine pages.

Brilliant, AW! I've been wondering about material for a bed and this stuff would be ideal. It's mega expensive if you have to buy a whole sheet, but offcuts would do fine for what I have in mind.

I feel a trip to my local kitchen/bathroom outfitters coming up to see what they may have.

Jeremy

 

[Thud]

Another thread off on a tangent :lol:
A Real problem for a vac system is the through holes for components.
Once you drill through you have compromised you holding power & it gets worse with every hole.
You will require an additional "spoil board" for every pattern you bore thru to be effective.(common practice)

If varying thickness is an issue on engraving, write a simple surfaceing program to plane a sacrafical board to "flat" as the machine see it, I hate UHMW for this as its so slipery. Scrap Corian or other solid surfacing material is great. then the 2-sided tape + a pc of foamcore as a backer(for drills to punch into) should be sufficent for short runs of pc.

The spring loaded tools solve a lot of problems. It allows a simple machine to function without an accurates"z" depth controll. & is will compensate for variances in the actual part being machined. (allways a problem in the wood industry)
True "Floating head" options are very expensive on the big equipment.
Vacume hold downs are great for holding all sorts of stuff. But knowing Luke he will spend 2 weeks building a perfect system....we need our boards ASAP

opps, i see jerremy responded as i am typing....hmnn I guess amberwolf meant SS countertop stuffs . not UHMWpoly cutting board stuff.
a very strong Vac source is a Venturie Vac generator powerd by compressed air. You can pull 28"m with a good unit.

 

[bigmoose]

The new LPKF machine in the "big lab" has a vacuum hold down. It uses a bizarre sheet of porous rigid foam. The white foam is 2mm thick and rigid. You cannot see through it. If you put it to your lips you can blow through it in the Z direction. I did not remove it to see the manifolding below it, I will try to do that next week when I am there. I think it is like a controlled porosity bleed for the vacuum system (it uses the shop vac to pull the board to this foam). I was playing with a new sheet a few months ago, slightly flexing it and it shattered instead of bending... the tech that runs the machine was a bit upset with me, said the stuff was reasonably expensive.

Looked it up... wow $100 a sheet! I owe him more than a cup of coffee:
http://www.lpkfusa.com/Store/pages/list.aspx?cat=6/27&cid=27

Link shows the honeycomb below the porous sheet of white plastic.

This looks like the manufacturer. Not that expensive when bought in a "real" sheet! Gotta love markup to the end user: About $16/ft^2
http://www.genpore.com/porous_plastic_sheet.htm

 

[oldpiper]

The new LPKF machine in the "big lab" has a vacuum hold down. It uses a bizarre sheet of porous rigid foam. The white foam is 2mm thick and rigid. You cannot see through it. If you put it to your lips you can blow through it in the Z direction. I did not remove it to see the manifolding below it, I will try to do that next week when I am there. I think it is like a controlled porosity bleed for the vacuum system (it uses the shop vac to pull the board to this foam). I was playing with a new sheet a few months ago, slightly flexing it and it shattered instead of bending... the tech that runs the machine was a bit upset with me, said the stuff was reasonably expensive.

Looked it up... wow $100 a sheet! I owe him more than a cup of coffee.

Yeah, you probably owe him a double iced cappucchino moca with caramel, whipped cream, and sprinkles (I don't know how to spell that stuff, I just ask the guy at the register for "coffee, with coffee" when I'm behind one of those who take 3 minutes to ask for all of their extras.

Cameron

 

[texaspyro]

A Real problem for a vac system is the through holes for components.

You usually just need the vacuum plate when milling. Drilling does not require the flatness that milling does. But then, removing and re-aligning the board can be a pain. Starting with good PCB stock and some double sided carpet tape has its advantages...

 

[amberwolf]

A Real problem for a vac system is the through holes for components.

If you use registration holes on the corners of the PCB that are alignable with the vacuum holes, you can use pins to insert thru the PCB into them to keep them from wiggling around, without having the vacuum system even running, though the vacuum would still help keep it from wobbling vertically if it's warped.

opps, i see jerremy responded as i am typing....hmnn I guess amberwolf meant SS countertop stuffs . not UHMWpoly cutting board stuff.

Not SS, but that plastic stuff--you know the really heavy stuff that looks like granite? It's made of lots of little plastic chunks all glued together with one polished side and one rough side (left that way to make epoxying pieces together easier, for one thing).


Keep in mind that as I've never used any kind of milling or CNC equipment, there may be things I haven't thought of that would cause a problem...but it certainly ought to work well as a vac table.

 

[liveforphysics]

Ok.

I dug through stacks of boxes of things (found some helicopters I forgot I bought, and a pistol I was missing LOL), and found the PCB board cutting bits.

First, let me say, the PCB cutting bits rock. You can make an extremely fine line through the board without the copper getting all torn up, but oddly, the fiberglass gets all puffy and snowy looking. With the micro-endmills, the copper would get ugly, and the fiberglass was cleanly cut.

So, I did 6 boards. All of them get 3/4th of the way through the program, board looking PERFECT, and then... the freaking spindle drops by some amount that makes the cutter nearly cutting THROUGH the whole board. The Mach3 software displays that it's still at -0.0152", but it's clearly much lower.

So, I ass-u-me-d the stepper was skipping steps on the first time I noticed the problem, and i had been running it at 200% speed, so I dialed it back to 100% and tried. Exact same point causes it to magically lower... so, I dialed it down to 50% speed, and it simply made no difference at all.

Now, my stepper for my z-axis, and my ball-lead-screw system are way way powerful. I've done stupid mistakes where the z-crashed down and just smashed the bit right into carbon fiber before the carbide shank broke off. It's a strong enough setup I'm sure it could carry me around riding on the spindle and go up-down all day long with no issues. So, I can't possibly see how dragging around this little needle-like bit in soft copper can make it skip a step on the z-axis, and that it would just happen to be at the same point everytime. Yet, the position display on the Mach3 screen indicates that it things it's still at the correct cutting depth, and the only way Mach3 knows position is by counting steps and assuming they all worked, so I'm guessing for some reason at some point in the code, something happens that has Mach3 thinking it successfully raised the spindle up, or something that inadvertently caused it to step-down and not count that step in the z-axis position.

Anyone have any clues about this guys? I tried this on a whole stack of boards at different speeds, same results. Notice things start out fine, looking great, then POOF! Deep wide trench that wipes out too much materials on each side so it ruins the board.

WTF am I missing guys?

 

[johnrobholmes]

Can you sort through the Gcode to see if there are any weird bits in there? You say it is happening at the same point in the CAM program?

 

[liveforphysics]

Can you sort through the Gcode to see if there are any weird bits in there? You say it is happening at the same point in the CAM program?

I don't know jack-squat about what I'm looking at when I review g-code. The code is up on this forum, it's the code for the power board.