Project opinions

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Xxray
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Re: Project opinions

Post by Xxray »

Something ain't right here, the sawblade is visibly and actually deeper on top and shallows out progressively as it goes around.

On the female walnut it is pretty obvious even eyeballing it, from about 3 oclock to 9 oclock it is much shallower and thinner than the top portion. The male poplar looks better visually but measuring it, it goes from .6 to .47 from 12 to 6.

You would probably say "Well, either your table is not level or the wood is flawed", I drum sanded the boards to a perfect .55 each and took pains to ensure I was level, they are flat as a board. Tried it twice with the same result, here is the file if someone can see a reason why the blade gets progressively shallower.
Unfortunately, looks like these prime pieces are good only for the firepit now, am not even going to attempt to glue them.

https://www.dropbox.com/s/ya124qe98ts0f ... crv3d?dl=0
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potzmannwoodshop
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Re: Project opinions

Post by potzmannwoodshop »

Xxray wrote: I drum sanded the boards to a perfect .55 each and took pains to ensure I was level, they are flat as a board.
so you have a +/- of .05 " or so, that could be how far off your drum sander is from being perfectly parallel.

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mtylerfl
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Re: Project opinions

Post by mtylerfl »

potzmannwoodshop wrote:
Xxray wrote: I drum sanded the boards to a perfect .55 each and took pains to ensure I was level, they are flat as a board.
so you have a +/- of .05 " or so, that could be how far off your drum sander is from being perfectly parallel.
He said a difference of 0.13" from the 12 to the 6 o'clock positions. (0.6" minus 0.47 equals 0.13")
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Re: Project opinions

Post by mark-s »

Xxray, what bit did you use and what was the deepth.
Thanks
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Re: Project opinions

Post by tomgardiner »

I suspect the bit creeping out of the collet. Did the depth of cut get deeper as the toolpath progressed?

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Xxray
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Re: Project opinions

Post by Xxray »

Measured the board in 4 corners, each was .55, so it was flat as flat could be. Consistent thickness and no warpage.

Bit was a 60 degree vbit.

I'm going to try pocketing a circle in some scrap wood and see if I can replicate this under the same conditions ,,, I'm doubting collet creep, I did the 2nd attempt on the other side of the same board and it came out exactly the same.
If you imagine a clock, the cut is consistent from 9 to 3 [going towards 12], gets progressively shallower the further it goes toward 6 either way. Sounds for all the world like a workpiece out of level or floating thickness, I have insured [twice] that it is not.

I think the deeper and wider cut at top is how it is supposed to be. The male fits in fine there and the boards are flush, at the bottom they are anything but flush. But this affected both pieces, they are both flawed due to the same gremlin so I am doubting if I can salvage anything [am thinking about cutting off the blade part with bandsaw and see if everything else will seat]
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Re: Project opinions

Post by potzmannwoodshop »

mtylerfl wrote:
potzmannwoodshop wrote:
Xxray wrote: I drum sanded the boards to a perfect .55 each and took pains to ensure I was level, they are flat as a board.
so you have a +/- of .05 " or so, that could be how far off your drum sander is from being perfectly parallel.
He said a difference of 0.13" from the 12 to the 6 o'clock positions. (0.6" minus 0.47 equals 0.13")
Yes .47 or .08 below .55 and .05 above or .60 +-.05ish

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Xxray
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Re: Project opinions

Post by Xxray »

Seems nearly certain to be a machine issue.

Tried a plain vcarved circle in flat, level scrap wood using the same setup and parameters, problem was replicated. Low side read .196 and high side was .114.
Tried again on the reverse, this time I cleaned out the collet [lots of gunk] and used a different vbit. Same results, so looks like for now my machine is not capable of making very accurate cuts for whatever reason.
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Re: Project opinions

Post by Rcnewcomb »

When was the last time you surfaced your spoil board? It might be as simple has that.
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Xxray
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Re: Project opinions

Post by Xxray »

Rcnewcomb wrote:When was the last time you surfaced your spoil board? It might be as simple has that.
Spoilboard is a horrendous mess and needs to be resurfaced/replaced, I should post a pic of it just for kicks - You wouldn't wish a spoilboard like this on your worse enemy.

Thing is, I don't cut directly off the spoilboard, I have a corian sub board on top of it that is independently and accurately leveled out, so in theory the corrupt spoilboard should not be a factor.
[Haven't done any diagnosing yet, pretty sure machine must be out of square]

I was going to burn the entire thing but the walnut was too pretty so I tried to salvage what I could. I took the male poplar part and cut out the saw blade with a bandsaw then glued up the remaining center parts. Exceeded my expectations, lettering came out nice along with the stars and emblems. Was going to leave it at that and probably should have, but I couldn't resist giving the saw outline a try, so I glued that up too and clamped it down overnight.

Looks pretty shabby at anything closer than 5 ft, some areas are fine and some are paper thin and lifting, I drum sanded it down best I could and put some clear coat on ,,, Still tempted to burn it, not sure if I will or not. Am not going to donate it to the hall as I originally intended, thats for sure. Probably give it to one of my buddies for a garage hanger.
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