Attaching spoil board question

[sudo]

Im about to attach a spoil board to my CNC Shark HD4.

In doing research, I came across this Glass Impressions video on doing just that. https://www.youtube.com/watch?v=3WSAiHsSGuk

In the video, imho, he uses way to many bolts. Is it really necessary to use so many bolts? I think he uses about 16 - 20 anchor points.

Im thinking that I can get away with 5. One in each corner and one in the middle. At most Im thinking 3 rows of 4 bolts for a total of 12.

Id love to hear how you guys attach your spoil boards. How should I go about it? Is it a 'more is better' situation or was Glass being overly cautious?

Thanks in advance!

[Rando]

If you're going to use the original surface of the spoilboard, I could see using lots of hold-downs, to make really sure the board has zero warp that might lift it off the table. But, if you're going to face the board using a fly-cutter or similar, then it doesn't make sense to use that many, and it makes it more likely a cut through to the spoil board will actually hit a bolt head. Plus, all those bolt heads countersink holes make the overall surface not a solid smooth surface.

(Disclaimer: I machine aluminum on my Shark, so I have vises. Early on I did use spoil boards; now I use machinist parallels to hold the part up in the vise so the bit can get to it.)

If the spoilboard covers the entire bed surface, I'd go with holes about 1" from the edges near the 4 corners and then maybe 4 more about 2-3" inboard from that, again in a rectangle, but now in the centers of the sides. If you then flatificate that with the flycutter, to me, that would be more than flat enough.

Hope that helps, but really I'm hoping to see how people are doing this.

Regards,

Thom

[bill z]

SUDO,

Are you a Linux system guy?

About your question: For my spoil board, I use nylon bolts and steel T nuts. If it hits a bolt, it will always be an accident but it doesn't have to be costly.

About putting too many or not enough, Just how much are you putting into the materials you are cutting (not the spoil board). If the spoil board has a warp and you spent, what $20. on the wood piece you are cutting and the cut is wrong because it wasn't flat, You will need more bolts and start with an new piece to cut.

Way back, I bought a 1.5 inch end mill to make sure my work top / spoil board is flat with respect to the router travel (travel, not table) I use every time I change out the spoil board. Take off just enough to give me the confidence that the board is true with respect to the router travel. Has not failed me yet.

Again, go nylon.

I do hope this helps in some way.

[Larry Stobbs]

I used mdf cut into strips. I bought the jig making nuts from NWA and then countersunk for five screws per board. The heads are well below the top surface so I didn't have to worry about a bit catching a bolt head. Unfortunately my HD didn't ever work so I never got to see how well it would hold up

[sudo]

Indeed, I am a linux guy. Remember kiddos, super users do

I ended up using 5 bolts; 1 in each corner and 1 in the middle. I then used a .75 straight bit to surface the MDF. Woah was that dusty.

Ive been using it a couple weeks and Ive noticed there is some play between the spoil board and the cnc table. Im hoping that the planed surface will make up for it....

Next time I think that I will use 4 rows of 3 bolts. Its extra work and getting the bolts to line up can be a pain, but I reckon its worth it.

Thanks again to all for opining.

[bill z]

Use the CNC to drill the holes for you. It can even counter sink them for you. They will be all in line and look real pretty.

sudo apt-get update tada

[Rando]

sudo apt-get update tada

Now you're just being mean....

[SKIF16]

I am another CNC newbie with a newbie question. What routine or program do I use to level my spoil board? I have the cutter but I don't know how to use it. I use a large piece of 3/4" MDF as my spoil board held down on four corners with clamps.

Cheers - SKI

[Kayvon]

SKI, all you need to do is create a pocket toolpath that covers the dimensions of your spoilboard. It doesn't need to go very deep--just enough to hit the lowest point on your existing board. If the board is nearly level, then your depth can be extremely small.

[SKIF16]

Thanks. It seems so simple now that you showed me what to do. Now all I have to figure out is how to display my leveling bit in the tool index of Vcarve. I normally just copy the info from a similar tool into my data base, but I cannot find a similar tool in the examples on the Vcarve tool index.

Check Six - SKI