Cutting 8' x 8" x 3/4" Greenheart hardwood

[associated]

I am quoting on cutting a huge amount of 8'x 8" x 3/4" dressed greenheart lumber for facia board.

I figure I can lay 6 against each other (to make up the 8' x 4' table) & hold down with a purpose made clamp type jig. Does anyone have any advice as to:

1.) What cutting speed/rpm I will be able to accomplish?

2.) Which bits to use for maximum speed, durability & finish?

3.) How often I will have to change bits?

I am quoting blind as my PRT Alpha with Portercable router has not arrived as yet & I want to hit the ground running.

Any help would be much appreciated.

[paco]

We would need more infos about your particular design to answer those questions. Are you making cutouts, carving, pockets, how many... How is actuate your hold down (screw, wedge, clamps, vacuum)?

[tuck]

Yeah, and the idea of stacking individual pieces together to make up a 4x8, somehow clamping them down, then cutting each piece without the bit getting into "where it shouldn't be" would scare the bejebbers outta me! :-0

[paco]

Mark,

you need this code to fix clamp (and such) collision:

&clamp_and_such = danger
&be_carefull = full retract against upmost bolt (or ask for operator assistance)
IF &clamp THEN &be_carefull
ON BIT BREAKAGE STOP AND MAKE WINDOW CRASH THEN WAIT

<8o)

[tuck]

LOL! Well, AMD, like Paco said, if you can provide some more info, I'm sure you can find some help here as to how to best go about it. It would be nice if you could post a pic (or a drawing), as to what the finished product looks like.

[associated]

Sorry, I was not ready for such quick responses. As`soon as I get in the office in the morning I'll post a pic & explain.

Thanks, Zak

[edp]

We do a lot of work here with green and purpleheart - Be aware that the stuff is very very hard and will dull carbide bits very quickly - it also has a tendency to split off corners when machining - the last fascia board job we did was in marine ply and was a walk in the park compared to greenheart. I would venture to say that marine ply will last a lot longer than the greenheart, which has a tendency to check and split fairly easily when exposed to the weather - if the client insists on using solid timber for the fascias he would be better off using purpleheart - greenheart is a superior timber for underwater work like piles and keels - purpleheart is better for abovewater uses.

[associated]

The design is very simple as you can see.

4826
I plan to place a load of 6, side by side as per picture & clamp with a purpose made jig. I am not exactly sure how I am going to do this but I am sure some type of hold down is possible that can be reloaded easily and quickly. Temp vaccum system, welded jig on hinges, loading boards etc

I have calculated from autocad the distance of the cut including the estimated jog distance and put speeds to them. The cut speed I am assuming is 1.5in/sec. I have come up with this just from reading what you 'botters' are sugesting from the forum.

One idea I read (can't remember where) would allow pieces to be removed and replaced as the machine cuts so the process could be continuous.

Edp, Thanks for the advice but my client only wants to cut greenheart.

Any ideas? Thanks, Zak

[associated]

Here is a crop of the layout. I am having trouble with uploading these pictures due to size and resolution. If it is not clear as to my layout I can email. Very frustrating. Anyway, what do you think? Zak

4827

[paco]

I would go with the idea of having a way to change part to blank as the tool cut... caution; plan ahead your toolpath (pauses, prompts)...

As for hold down and JIG, I'll leave that to you right now... have you consider a pallets (2) system?...

For maximum efficency, I would chuck in a 1/2" CED bit; I would choose compression but straight carbide tipped will do the trick. Compression may/will make clean cut without required secondary sanding... plus these are VERY aggressive cutting tool. Stay with short CEL tool for maximum rigidity and economy. I'm not sure of what is that kind of wood, but if it pretty hard, 1.5"/sec. might be a maximum with a PC router mostly if you plan (try) to cut in a single pass...

[paco]

Plan room for kerf...

[associated]

Thanks Paco, Also, where can I find these bits? Whats a kerf? and how much faster do you think I could do it with a spindle? I ordered the machine with the spindle wireing already setup so it is just to ship it in.

[paco]

If you Google "router bits", you should find "some" supplier (hi, hi , hi!)... I'm pretty much sold on Onsrud for a matter of simplicity.

The kerf is what's get remove from the tool bit diameter as it cut; a 1/4" CED will theoretically remove 1/4" wide of material. I've point this out since I didn't see any space left in between each of your part in the above drawings.

I'll let other fellow Botters equipped with spindle chime in... but you'll do better with a spindle I believe... even more if get into massive production.

[mikejohn]

AMD

I regularly cut boards 14mm (6") x 2,4m (7'6") x 20mm (.8") laying five up on a simple pallet system.
Laid out like this
__________________________________
E
__________________________________
D
__________________________________
C
__________________________________
B
__________________________________
A
__________________________________
then, starting at A, when the 'bot has cut A and B, and starts on C, I slide out, and replace pallet A. When cutting D slide out B, cutting E slide out C and so on.
The boards are firmly attached to the pallets (25mm thick MDF the length of the table, 200mm wide) then the pallets simple attach to fixed bolts at each end.
The 'bot never needs to stop.

.............Mike

[hespj]

When I do stuff like this I

i)....mark where the planks are to go on the table - say 10" centres
ii)...Screw the overlength planks to the table at the ends only (in waste material)
iii)..Run the first cut file which only drills the holes (the 0.25"R holes you have indicated)
iv)...Screw down the parts using a few of these holes
v)....Cut the parts (use the chipload calculator in the SB software to help decide cut speed, but it will considerably faster than the 1.5"/sec you assume).

[zeykr]

Mike, can we see a picture of your pallet system. Think you've talked about it before, but I can't seem to find it in search.

[associated]

Thanks guys,
Mike: How do you attach the boards to the pallets? Yeah, lets see a picture.
John: Thanks but it does not sound fast enough to go continuously. Or am I not understanding correctly. It has to be quick as this is a pretty big order.

[mikejohn]

Gentlemen
A new (but similar) pallet is being constructed as we speak.
I will post some pics of the whole procedure in a couple of days.
Not my idea, by the way, came via (suprise,suprise!) Gerald.
(My design though
)
..............Mike

[associated]

Hi Mike, Hows the pallet coming along? :-)
Zak