Spoilboard milling

New Home Forum LowRider Advice – LowRider Spoilboard milling

This topic contains 34 replies, has 8 voices, and was last updated by  Ryan 4 months, 2 weeks ago.

Viewing 30 posts - 1 through 30 (of 35 total)
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    Posts
  • #88196

    John
    Participant

    Hey,

    So I wanted to get my spoilboard flat and even with my router.  The biggest flat bit I have is 19mm wide.  At 1mm depth, to cover an area of 2440 x 1220mm will take something like 40+ hours, at 20mm/s.  Even if I was to run it at 50mm/s, it would take 17 hours.

    What am I missing?  Do people invest that many hours in doing their spoilboard?  Do I need an extra large bit?

    What’s everyone doing?

    Thanks

    #88206

    Jeffeb3
    Participant

    I don’t think anyone is surfacing the whole low rider. I proposed a couple of times that someone should use a frame and flatten that, then attach the spoil board to the top.

    But really, what are you doing that requires surfacing the whole thing?

    #88234

    John
    Participant

    20190209_101437
    I remember you had suggested that when I was building my table.  I might take the sheet off and do that.   I have about 1mm drop on the opposite side diagonally .

    #88237

    Barry
    Participant

    I have a 1 inch surfacing bit.  Haven’t surfaced the lowrider yet.  I need to though, I’m planning on a full sized 3d engraving, so I need it flat!

    #88244

    Jeffeb3
    Participant

    I have about 1mm drop on the opposite side diagonally .

    That is pretty small for a cnc this large. But those are through cuts, just add 2mm to you cut depth and cut those guys out. The spoil board is meant to be spoiled!

    I’m planning on a full sized 3d engraving, so I need it flat!

    Have you looked at how the carving will take?

    #88251

    John
    Participant

    The spoil board is meant to be spoiled!

    Hehe, yeah you’re absolutely right.  I set my height with the intention to only just penetrate the bottom and marking the spoilboard as least as possible.

    @jeffeb3 I have just removed the spoilboard and am manually (with the knob) manoeuvring the router and surfacing the 2 x 4 underneath.  Actually it’s not taking as long as I thought.  Another half hour and I’ll be done and ready to screw the spoilboard back in

    #88278

    Jeffeb3
    Participant

    Cool! I hope it works as well as it does in my head!

    #88322

    Barry
    Participant

    I’m planning on a full sized 3d engraving, so I need it flat!

    Have you looked at how the carving will take?

    Not yet.  I’m going to split up the gcode at every layer.  I still need to end stop the lowrider too.  It’s going to take days though.

    #88327

    Jeffeb3
    Participant

    Not yet. I’m going to split up the gcode at every layer. I still need to end stop the lowrider too. It’s going to take days though.

    Take lots of pictures!

    If everything is carved, like no surface left, then the Z won’t actually matter much.

    #88338

    Barry
    Participant

    Not yet. I’m going to split up the gcode at every layer. I still need to end stop the lowrider too. It’s going to take days though.

    Take lots of pictures!

    If everything is carved, like no surface left, then the Z won’t actually matter much.

    It’s going to be a table top, so like 1.5-ish inch thick wood.  My cnc table has a slight hill in the center of the y travel.  Not an issue with sheet goods, they flex, but the solid wood top will teeter totter over that hill.

    #88394

    hobbyhack
    Participant

    I am new to CNC.  However, if you are not cutting through you might just be able to shim the work piece.  You could mount a dial indicator (harbor frieght sells a decent one for $15) and just measure to get your high and low points.  You might also be able to use the dial indicator to know where you need to surface your spoil board to avoid having to surfacing the whole thing.

    #88398

    John
    Participant

    Thanks, I’m pretty new myself, but I did get it sorted.  I did what Jeffe said and had suggested when I was building it (I was in too much of a hurry to do it lol) but didn’t at the end.

    So I took the spoilboard off, manually (with the lcd knob) routed all the 2 x 4 underneath and although I haven’t tested it yet (that’s another story) it actually took off around 3 mm from some places and none at other spots.  Now there’s a groove where the spoilboard just drops in.  Won’t be able to test it with the router because I killed it.

    #88399

    Jeffeb3
    Participant

    Won’t be able to test it with the router because I killed it.

    Oh no!

    #88401

    John
    Participant

    Literally 1 more minute and I would’ve finished before it died.  It’s kinda my fault though.  As it was cutting, it came to a pretty deep part (around 4mm) and it stalled.  I reached for the switch and turned it off, and it got going again for almost one pass then it died.  I didn’t have the RPM up full, if I did it may not have stalled.  4mm doesn’t seem alot, but at half the RPM with a 19mm surfacing bit, it takes quite a bite.  I ended up finishing the rest of the 10cm that was left with my hand router.

    I’ve ordered another one and it’ll be here in a few days.  Not sure if died because it’s the cheapie makita look-alike, or not.  I don’t know if the better brands have protection for things like that, but regardless, there was absolutely no smoke at all, it just peacefully gave up

     

    #88418

    Kelly D
    Participant

    regardless, there was absolutely no smoke at all, it just peacefully gave up

    That’s the worst way to go! Hahaha……my electric saws go in fits of sparks and smoke and bad burning smells. And if they don’t, chances are if I let them cool right down they’ll fire up again and go till they do! ; )

    #88452

    Jeffeb3
    Participant

    Are you sure it isn’t just thermal shutdown? The brushes are replaceable too, although it usually sounds quite funny when they go.

    It’s also got a manufacturer’s warranty. That might be something to look at. The dewalts are great for that.

    #88475

    John
    Participant

    I was hoping it might’ve been thermal shutdown, but after a day and it still won’t go.  Brushes are still almost new.

    I have  contacted the seller I bought it from, waiting for reply.  It does have a 2 yr waranty.

    #88508

    Barry
    Participant

    Not yet. I’m going to split up the gcode at every layer. I still need to end stop the lowrider too. It’s going to take days though.

    Take lots of pictures!

    If everything is carved, like no surface left, then the Z won’t actually matter much.

    Holy crap!  Just threw it in estlcam to get a rough idea.  Might have to change my plans.  37 hours just for the roughing pass!  That’s with a quarter inch end mill.  46 hours for the finishing pass.

    #88540

    John
    Participant

    Yeah exactly what I was saying lol

     

    #88580

    Barry
    Participant

    Yeah exactly what I was saying lol

    Surfacing the spoil board will only take 4.5 hours with a 1 inch surfacing bit.

    #88585

    Jack
    Participant

    If your work can easily do without surfacing, do without if you want.

    To be technically correct and don’t want to loose any thickness of your base that you would otherwise use as a spoilboard, I think glue down an oversized piece of MDF, let it dry, then surface the MDF as needed.  Then if the spoilboard starts seeming to thin, just glue a new MDF sheet on top, resurface if needed.  That way you always have some sacrificial spoil board available. … Just a thought (stolen from other forums ..grin..)

    #88687

    Barry
    Participant

    My spoil board is screwed down to the plywood table, so no worries there.

    #88691

    John
    Participant

    The plus on surfacing the table frame (2×4’s) rather than the actual MDF spoilboard is that whenever I need to change out to a new spoilboard, I just unscrew the old, screw in the new one and it will still be level because I’ve levelled the frame, not the spoilboard, and ontop of that it only took me a couple hours compared to 40 that was predicted by Estlcam

     

    #88692

    Jeffeb3
    Participant

    John, I’m excited to see if that worked for you. On my (smaller) low rider, I cut a bunch of 2mm holes in the spoil board (about 1/4″ diameter, IIRC) and used digital calipers to measure the actual depth I got at various places around the machine. I posted it here somewhere and it was interesting. I wonder what you’d get with a test like that. I would consider anything under 1mm to be good, and anything under 0.1mm to be perfect.

    #88693

    John
    Participant

    I’ll try that some time on the weekend I reckon.  It would be interesting to see.  I don’t think it would be perfect, as for one thing, there were a couple places where the bit didn’t quite touch the 2×4’s when I was surfacing them, but only a couple spots.  Ultimate for me would be to be able to add 0.4 to my DOC and have all the pieces go right through on the whole sheet.

    Depending on the results I get, I might do another pass to try and get to those parts that didn’t get touched last time

    #88697

    Jeffeb3
    Participant

    0.4mm on an entire 4’x8′ sheet is very very good.

    #88700

    Jeffeb3
    Participant

    Depending on the results I get, I might do another pass to try and get to those parts that didn’t get touched last time

    The sheet is going to sit on the highest parts, so if there is a bump where you didn’t get, but it’s only 1/8 of the 2×4, then you can knock that part down with a chisel, even.

    On big, big hand tool workbenches. The kinds made from solid lumber, there is enough movement that they need to be flattened a few times. When you remove some material, the internal stress of kiln dried lumber will release, and change the shape a little. That, plus the moisture content changes with the seasons. If the process to flatten it is easy enough though, and you have a decent way of measuring it, then you’ll probably have a lot more credibility on how often to flatten than any of them in a year or so.

    #88703

    John
    Participant

    0.4mm on an entire 4’x8′ sheet is very very good.

    Yeah I never said it was gonna happen lol.

    The sheet is going to sit on the highest parts, so if there is a bump where you didn’t get, but it’s only 1/8 of the 2×4, then you can knock that part down with a chisel, even.

    No no, you lost me there.  The part that didn’t get flattened was too low when the bit went over it.  So to try and get it as perfect as possible, I would need to do another full run, maybe 1mm lower to see if the lower parts will even out with the rest.  It was 2 spots that were lower if I remember right, half way up the long side, on the right hand side of the table.  At a guess, probably about a 500x500mm square area.

    #88725

    hobbyhack
    Participant

    Glad it is sorted.  Sorry to hear about the router.

    Marlin firmware also has an manual mesh bed leveling feature.  It is really simple to use and only requires a cheap dial indicator and a mount for the indicator.  I use it on my 3d printer and it helps a lot in some circumstances.

    It might not be enabled in the MPCNC/LR firmware build.  But it is an option to consider.

    #89403

    Barry
    Participant

    Got it down to 2 hours, upped the speed to 30mm/s, and I’m pretty sure I can go faster.  While all this was happening, I finally got around to upgrading the mpcnc with the burly parts.  I think I was the second or third to finish printing them..  I blame the weather. ?

    Really shows how not flat the table is though.

    https://t.co/d8EN2iA6dV   <<<—  Speaker warning!!  Turn them down.

    Here you can see how not flat my “flat” torsion box framed table is.  Not sure how much the room has moved though.  The last 8-ish feet of the room actually overhangs the outside wall of the barn’s basement floor.  I know the barn moves seasonally.

    Had the vac running the whole time, even though the above picture shows a bunch of dust on the board, all this was sucked up, there’s about 6 inches of mdf dust in the bucket.  There’s none in the shop vac bucket, and the vac’s filter didn’t clog, so not too much made it past the dust deputy.

    The surfaced surface isn’t that flat though.  Once I started running the job I noticed the carriage has a slight tilt to it.  Looking at the table, the side closest to the flag in back sits lower than the other side.  Not sure why, it sits flat plastic to plastic when the steppers are deenergized.

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