Spoil Boards for Beginners

[Bryan Cowan]

With my MC-2840 from CAMaster on the way, I need to be prepared for delivery. One item in particular I'd like to get squared away is the spoil board.

From my research, MDF is the material of choice, but at what thickness?

Onsrud recommends their 91-100 bit to surface MDF spoil boards. How deep into the board is recommended to have a perfect surface? Are there better surfacing bits available?

What else should I know about spoil boards?

Thanks,
Bryan

[Nicholas Bukky]

Bryan,
Do you have a vac table as well? I use a 1.25 CMT bit on my spoil board and it takes about 20min to do my 4x8 table @ 300 ipm.
I usually use .75mdf but I had a sheet of .5 on hand so I used it this time.
I typically go about 1/16 into my spoil sheet each time I clean it up.

I keep thinking about getting a larger spoil board cutter, the one from centurion tools is $225 I think and 2.5inch with indexing cutter tips.
I only have about 35 or 40 in the cmt bit and it does fine.


Just my thoughts!!
Nick

[james mcgrew]

i am with nick, a 1.25" dado does a fine job and saves money i have yet to replace it in 2 years all it does is clean spoil board, more than likely unless you are using vacuum you can counter sink screw it down clean a 1/16th for flatness and screw your aluminum to the table cut thru should be just enough to give the desired edge on the bottom after cut and no more. i simply sand mine a bit and move on.

might call chuck hicks at south east tool and tell him what you are cutting and find what bits you will need ( tell him what you bought and you will get a discount)

jim

[Bob Savage]

i am with nick, a 1.25" dado does a fine job and saves money...

might call chuck hicks at south east tool and tell him what you are cutting and find what bits you will need ( tell him what you bought and you will get a discount)

Noted for future reference. Love this place.

[Michael Kowalczyk]

Bryan,
Do you have a vac table as well? I use a 1.25 CMT bit on my spoil board and it takes about 20min to do my 4x8 table @ 300 ipm.
I usually use .75mdf but I had a sheet of .5 on hand so I used it this time.
I typically go about 1/16 into my spoil sheet each time I clean it up.

I keep thinking about getting a larger spoil board cutter, the one from centurion tools is $225 I think and 2.5inch with indexing cutter tips.
I only have about 35 or 40 in the cmt bit and it does fine.


Just my thoughts!!
Nick

Hey Nicholas,

20 minutes to surface a spoilboard. OUCH

Time is money and if your CNC can handle it I would recommend getting a 2"-3" inch surfacing bit. The one with inserts works well too. I think we do our 5' x 8' table at 800 to 900IPM and it takes less than 5 minutes. I will check and repost if it is different. We take off maybe .010" (The main reason we may need to resurface is because of humidity. that's why we only need to take off .010") at a time because we use a 1/4" MDF carry board to do the main work. It is a lot cheaper than having to resurface your table and pay big bucks for a larger vac. We use a 20 hp Travaini Dynoseal at about 360 CFM and can maintain 18 to 25 inches of merc when using this method.

If you are doing this as a hobby, time may be more readily available than $$$ so your bit may suffice for now or longer.

Thanks and ...

[Guy Mathews]

Sorry Bryan,

I tried to PM you today on this but the DSL at work was acting up. Since you are primarily buying this machine to cut aluminum, you may want to stay away from MDF because of the mist fluids you will use to keep your bits cool. My table came with the standard black sealed top and T slot aluminum. From there I secured 3/4 ply to the table and surfaced that. I left a small spot open for using the T-slot for small piece work that I use a drill press vise or two for holding stuff in place. I am sure I mentioned to you that screwing your piece to the table is okay if you are only doing a few pieces.

Since your machine is about production, you are going to need to rethink the screw down method. Time permitting, I will email you a photo of a jig I made that uses small captive T-nuts and bolts to hold the piece to the table. The whole jig is clamped down to a fixed location on the table. The stock is secured at the corners and the machine does the boring of the holes. When finished it moves to a safe location on the table and a G4 code is used to pause the machine for 45 seconds. During this 45 seconds the operator blows the debris from the table and the holes and inserts the bolts and tightens down the piece. When the time is up the gantry comes back to cut the piece. It is important to note that this type of operation requires a good operator who is paying attention. I also write the program so the operator is on the back side of the gantry. This way, as the machine comes back, the gantry and not a running spindle nudges the operator out of the way!

Jigging and fixturing are going to be 2 obstacles you will have to overcome. Small vacuum jigs would be good for your application.

As for spoilboard surfacing, this has been covered a lot. The video to Chris Farley in the youtube link no longer exist. I hope the poor guy that had it on Youtube did not get into trouble. Anyhow, check out this thread as far as surfacing goes. http://www.sawmillcreek.org/showthread.php?t=112610

Also if you do a search on "vacuum jigs" or "vacuum clamps" either here or Google, I am sure you will find some neat ideas for holding down your aluminum parts.

Guy

[Bryan Cowan]

95% sure I am not getting the vacuum table. Perhaps I fully don't understand what a spoil board is? To me, a spoil board is a sacrificial board that will get cut and routed as my parts are being processed. This is to protect the table top surface of the machine.

I've read where spoil boards are directly related to being held down by a vacuum and where MDF is one of the recommended materials. Considering I won't have a vacuum table, I need to secure my work pieces in another fashion.

In this case, how important is surfacing the spoil board?

Guy,
While the machine will be used for production, it's not "production" in the normal sense of the word. Depending on how good I become at it, I may only run the machine 1-2 hours per day. If the easiest solution of holding pieces down is to screw them down, I think I'll be fine initially. Once/If production picks up, we'll find alternative methods for holding work pieces down.

Bryan

[James Jaragosky]

95% sure I am not getting the vacuum table. Perhaps I fully don't understand what a spoil board is? To me, a spoil board is a sacrificial board that will get cut and routed as my parts are being processed. This is to protect the table top surface of the machine.

I've read where spoil boards are directly related to being held down by a vacuum and where MDF is one of the recommended materials. Considering I won't have a vacuum table, I need to secure my work pieces in another fashion.

In this case, how important is surfacing the spoil board?

Guy,
While the machine will be used for production, it's not "production" in the normal sense of the word. Depending on how good I become at it, I may only run the machine 1-2 hours per day. If the easiest solution of holding pieces down is to screw them down, I think I'll be fine initially. Once/If production picks up, we'll find alternative methods for holding work pieces down.

Bryan

Think of surfacing the spoil board as leveling it.

[Jim Underwood]

I work in a cabinet shop where we routinely surface the spoilboard. We have a 3 or 4 inch flycutter running fairly fast. I don't remember the speed or how long it takes- but it's only a few minutes.

The reason to re-surface the spoilboard is because you typcially cut through your parts about .003"-.005" and it leaves a lot of grooves. When you get enough grooves in the spoilboard, then the vacuum leaks out from under the parts and they start to move around on you. So spoilboards tend to be strictly vacuum pump related items.

And MDF doesn't like getting wet- at all.

[Robert Alexander]

Sorry Bryan,

I tried to PM you today on this but the DSL at work was acting up. Since you are primarily buying this machine to cut aluminum, you may want to stay away from MDF because of the mist fluids you will use to keep your bits cool. My table came with the standard black sealed top and T slot aluminum. From there I secured 3/4 ply to the table and surfaced that. I left a small spot open for using the T-slot for small piece work that I use a drill press vise or two for holding stuff in place. I am sure I mentioned to you that screwing your piece to the table is okay if you are only doing a few pieces.

Since your machine is about production, you are going to need to rethink the screw down method. Time permitting, I will email you a photo of a jig I made that uses small captive T-nuts and bolts to hold the piece to the table. The whole jig is clamped down to a fixed location on the table. The stock is secured at the corners and the machine does the boring of the holes. When finished it moves to a safe location on the table and a G4 code is used to pause the machine for 45 seconds. During this 45 seconds the operator blows the debris from the table and the holes and inserts the bolts and tightens down the piece. When the time is up the gantry comes back to cut the piece.

Guy

Guy, could you post a picture of your jig, so the rest of us can see what you did?
Thanks in advance

[James Jaragosky]

I work in a cabinet shop where we routinely surface the spoilboard. We have a 3 or 4 inch flycutter running fairly fast. I don't remember the speed or how long it takes- but it's only a few minutes.

The reason to re-surface the spoilboard is because you typcially cut through your parts about .003"-.005" and it leaves a lot of grooves. When you get enough grooves in the spoilboard, then the vacuum leaks out from under the parts and they start to move around on you. So spoilboards tend to be strictly vacuum pump related items.

And MDF doesn't like getting wet- at all.

Not all of us have vacuum tables, but all of us use a spoil board. I need to resurface mine because humidity will cause some points to raise higher than others. so I resurface to level the table.
Jim J.

[Bob Savage]

Not all of us have vacuum tables, but all of us use a spoil board. I need to resurface mine because humidity will cause some points to raise higher than others. so I resurface to level the table.
Jim J.

Do you just resurface regularly, or do you have a 6' (or so) foot level/straight edge for checking it?

[Nicholas Bukky]

Hey Michal,

My router could probably handle about 500ipm max and I know I could do it faster with the bigger bit but I don't do high production so it's OK.

I am a one man fixture/cabinet shop and mostly do one off prototype stuff.

Maybe someday I'll move into big production work but that would take employees and I don't like the idea of more mouths to feed!

Bryan let us know how it goes!!

Thanks,
Nick

[James Jaragosky]

Do you just resurface regularly, or do you have a 6' (or so) foot level/straight edge for checking it?

If the job requires tight tolerances I will resurface just for that reason. otherwise you can tell when it needs done.

[Steve knight]

amana sells a 1 3/4" mortise bit for about 35.00