Intro and dumb questions about Desktop Max

[WaltzWorks]

Hey everybody

As I mentioned on another thread, I just pulled my first CNC machine out of the crate on Monday. My wife's side sign & gift business has been pretty successful so we spent the proceeds (and a bit of our personal $) on a serious upgrade to her Cricut :-)

I'm brand new to CNC but I've spent my entire career dealing with CAD and 3D modeling (architectural BIM software to be specific). I've already gone through all the Vectric tutorials and am picking up VCarve pretty quickly.

I've run into a few issues in my first week and I'm not finding anything in the search because I don't know the right terms to even use for this, so I hope you'll forgive a few dumb questions early on. I promise, I will learn quickly and be a contributing member soon!

My most annoying problem so far is this one: when I surfaced my spoil board, there were lines running parallel to the gantry (Y axis?). I also see the same thing any time I use my 1/2" bit. I'm guessing the spindle isn't exactly square to the table, but I can't quite figure out how to tell or how to even measure what I'm guessing is a decimal of a degree so that I don't overcorrect and have to re-run the routine and trial-and-error it 20 times. Does anyone have a recommendation for how to measure and correct this?

[bleeth]

The best way to check it is by rigging up a trammel and using a dial indicator and/or feeler gauges.
Just take a stiff wire that is close enough diameter/wise to chuck up in your collet and bend it so you have the end point close to your spoilboard and a 6" or so radius and check by rotating the head by hand.
Desktops are supposed to come with z properly plumb to start with. Once you have your trammel rigged up you may want to get hold of SB support.
Specific experience on a Max is going to be in short supply here for a little while since it is so new.

Where in the suburbs? I'm old Philly family and was born in the NE.

Dave

[scottp55]

If you can't catch the ridge with your fingernail, then not normally a problem with a 1.25"cutter.
Here's a good thread Tom from exact to stone age,
Currently Fred Flintstone $2 18" brass rod myself, but no grooves at all.
Good thread here, and doing it on a new board Monday on second desktop Monday.
http://forum.vectric.com/viewtopic.php?f=2&t=21172&hilit=trammel
scott

[WaltzWorks]

Thanks, Dave, that's about what I figured. I'm out in Downingtown.

Scott, that thing looks pretty nice but a bit pricey... still kind of tempting! i like the idea of doing it cheaper.

[Keith Larrett]

I also found I get better results not using the surfacing routine that came with my machine. I found another online "Paco's Surfacing Routine". Instead of surfacing in ever decreasing rectangles, it gives you the option of surfacing in either the x or the y direction. Also, very handy when surfacing a slab as you can cut in the direction of the grain.

http://pacosarea.blogspot.com/2007/02/surfacing-along-axis-shopbot-routine.html

[bleeth]

Paco's surfacing routine is much faster for surfacing spoilboard but you don't get to see those "telltale" marks in the opposite direction that let you know your z is plumb (or not).

Great board surface routine.

[tri4sale]

Paco's surfacing routine is much faster for surfacing spoilboard but you don't get to see those "telltale" marks in the opposite direction that let you know your z is plumb (or not).

Great board surface routine.

What are these "telltale" marks you speak off???

[bleeth]

When you run the standard surfacing routine inspect the "tracks" left in the surface.
They will look like a miniature mowed grass pattern.
If you can feel the edges between them your z is out of alignment either from needing shimming or adjusting v-rollers and/or rails.
How the edges are left tells you which direction you are out.
Same as your PRS

[James M]

bleeth,

Could you expand on your statement: "How the edges are left tells you which direction you are out."

I noticed some slight undulations on my spoilboard last time I re-surfaced it.

Thx,

James

[bleeth]

If you are out of plumb then the bottom of the bit will not be level so there will be slight ridges left in the spoilboard.
If you slide your fingernail across the paths you will feel which side is higher. If it is higher towards y-0, for example, that tells you your spindle is slightly tilted with the bottom closer to y-0 than the top

[jerry_stanek]

I agree if you surface in the circular method you will see if your z is plumb then if you surface back and forth either in the x or y and not get any ridges then your board is smooth but your z is still not plumb

[WaltzWorks]

Thanks for the help, everyone! I was able to get the spindle back in line.

Now I've got another problem: doing the classic pocketed letter sign, I'm finding that I have weird little raised and depressed circles in places. In some spots it looks like the 1/2" bit dug just a touch too deep and in other places it looks like it was a bit too high and the 1/4" cut around the high spot.

I made sure to zero the Z in the same X-Y location for each bit and I've got a hold down on all 4 sides of the sign. When I took the sign off, I held it to a level and it doesn't seem to be warped or cupped.

Does anyone have any other ideas for possible solutions?2752227523

[steve_g]

Tom…
To me it looks like classic material movement due to stress relieving or movement due to moisture content of the board reducing deep in the board after its guts were exposed. The small amount of movement we’re talking about here wouldn’t be noticeable with a level.

Solutions…


You might try some double stick tape under the interior of the sign as well as your perimeter hold down.
Complete the project as quickly as possible before it can dry out from the newly exposed wood. If you’re cutting with a router, its down blast of hot air can dry out wood with a high MC, try to deflect it.
Try a more stable substrate.
What bit are you using? A down cut bit wouldn’t try to suck the material up…

This is where I’d start… hope it helps! Let us know!
SG

[WaltzWorks]

Thanks, Steve!

1) You're right, I'm only holding down at the perimeter.
2) I was using a 1/2" bit to try to get it done faster. I don't know how to move it faster than that :-)
3) I've got an MDF spoil board. Would I be better off holding down straight to the aluminum deck?
3) It's a 1/2" spiral up and a 1/4" spiral up. Should I use a down for both instead?

[steve_g]

Tom…
By “as quickly as possible” I was suggesting that you don’t cut one path today and another tomorrow! Sometimes on very large signs, that’s not entirely unreasonable…
My preference is to cut on MDF… it’s only a matter of time until you (me) do something brain dead and cause the bit to dive through the project into the spoilboard!
I don’t know how large your total project is, often the time you save doing a bit change is inconsequential. Personally, I hate doing a bit chance and will design around it!
I’d certainly have down cut bits in my arsenal… it might even help with the chip-out you’re having on some letters.
SG

[scottp55]

Tom,
Did you get the starter bit set? May want to try using the .25" Onsrud down for everything just once for comparison?
Then maybe buy something like the Centurion .25 and .5" FEM downcut if you like the .25"downcut results.
http://www.centuriontools.com/router-bits-toolcase/solid-carbide-wood-router-bits.html?sku=12DS21.1253FEM&pcn=Downshear&pid=767&sat=1
Personally found best pocket surface was with less than .02" cut as a last pass and use a center cutting downcut with conventional toolpath.
Under "edit passes" look at last pass.
I see Steve has mentioned some of the same things:)
scott

[WaltzWorks]

Thanks, Steve. I thought you meant like I needed to speed up the process somehow :-) Most of what I'm doing are in the 9x23 to 11x28 size range. Nothing big. I'm assuming that the 1/2" bit is quite a bit faster... and I have to correct something I said earlier. My detail bit is 1/8", not 1/4".

I was a bit paranoid about removing the spoilboard, so I'm glad to hear you say that!

[WaltzWorks]

Scott,

I did get the starter kit. I just realized I said I was using 1/2" and 1/4". My smaller bit is 1/8".

I'm still too new to know what I do and don't like yet as far as bits go.

Random question: would a vacuum table help with the movement/stress relief issue at all?

[scottp55]

Try using the 1/4" down AFTER running the 1/8" super O 61-040 for less tearout(not really the best bit for good pocket finish)
For a very good pocket finish with a .125" bit , I've had very good luck with this one, but you need an 1/8" collet(you should have one anyways).
If you can get away with .5" LOC.....Says soft plastic but used with Bloodwood/Purpleheart and Teak no problem.
http://www.ebay.com/itm/1-8-1250-CARBIDE-2-FLUTE-ENDMILLS-DOWN-CUT-FOR-SOFT-PLASTIC-/151926815022?hash=item235f8b392e:m:mrZpBbbuK5RaQbY Iqs2btnw

I like his 16'th downs also and do all our buttonholes with them....pretty happy with all his stuff, and Very reasonably priced and fast shipping.
I might try his engraving bit selection(enter them as VBits even though they have a .012" flat) only one I had problems with was his 30 degree "Sharp" which has a .006" flat on it which myself and a friend had tips breaking off..otherwise my go-to's for tiny stuff and fairly painless for "Oopsies"
http://www.ebay.com/itm/SET-OF-10-MICRO-ENGRAVING-TOOLS-30-through-120-degrees-Kyocera-Tycom-/381480846723?hash=item58d207c583:m:mT_Y1Y-4I7gJ0iPQPUDHvEg
No idea on Vac.
scott

[steve_g]

Tom…
The FEM bits that Scott has recommended are bottom cutting bits, they will generally give you a better finish in the bottom of a pocket. Regular (non FEM) bits have a swallow tail look on the end and cut on their perimeter while moving, but leave swirl marks. Typically a FEM bit wants to be ramped into its cut.
SG

[WaltzWorks]

Thanks, guys. It looks like I have a little experimentation to do and maybe some shopping while I'm at it!

[scottp55]

Thanks Steve, I ramp almost everything so forgot to mention.
Tom, Maybe mess around with some small test pieces with the 61-040 doing everything.
I got some good experience with that bit testing stuff when it was the only 1/8" I had.
scott

[bob_s]

Scott
Nice detail About how big are the blocks and the Tatum plaque
thanks
bob

[scottp55]

Thanks Bob,
Tatum was 4.5X9" and Freestyle Script which looks better pocketed than VCarved.
That was a text test for kid's blocks so would have been 1.75" with a 3/16" R pointed roundover for simulation.
Both in Hard Maple.
Tatum feeds/speeds are closer to what I wound up using on the first test piece.
scott

[WaltzWorks]

The 1/4" down spiral with a final pass seemed to really help.

Now onto my next issue... learning to finish!