Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Feb 4, 2013 11:08:35 GMT -8
I was wondering if anyone would know why it is that when I carve something starting out with a kiln dried straight board, after carving the wood begins to warp. Sometimes even warps against the grain direction.
|
|
|
|
Post by Greg on Feb 6, 2013 19:44:41 GMT -8
Hey Bob
I had a lot of boards do that most of them had knots somewhere but moisture in the air will do it too.
I bought some real nice boards from Home Depot they call them "select" and they cost $25-$50 a board but they dont warp as bad.
You can fix the ones that warp I place them under a heavy ammo box for a week inside the house then I put finish on them to keep out the moisture.
Greg
|
|
|
|
Post by gullyfoyle on Apr 10, 2013 11:00:26 GMT -8
I was wondering if anyone would know why it is that when I carve something starting out with a kiln dried straight board, after carving the wood begins to warp. Sometimes even warps against the grain direction. One of the other CNC forums claimed it was due to stress because of the carved section not being enough support. Something along those lines. |
|
|
|
Post by Greg on Apr 11, 2013 0:45:24 GMT -8
Just to follow up I have had zero problems with the "A" grade boards not one has warped also one of the boards I bought was a 12" wide MDF I like the way that does too.
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Apr 11, 2013 4:23:01 GMT -8
Factors that determine whether or wood will warp are the extent and distribution of internal stresses in the wood. When you machine wood, you may alter those factors in a way that leads to warpage......I read the preceding from a woodworking site. The grow rings in wood typically warp back toward the former center of the tree, so when ever I am carving a piece I place the grow rings facing down on the table and logic would say that any warpage would go in that direction but that has not been the case. It was my belief that there is tension in the wood that gets altered when carved and that sort of confirms. I am buying my wood from a local lumber mill where I'm getting really nice kiln dried 6-9% moisture boards that are 4/4 or 5/4 thick and in up to 12-13" wide. An example would be a 13" wide , 4/4 thick x 12 ft. red spalted maple board I recently bought:: $ 49.00
|
|
|
|
Post by gullyfoyle on Apr 11, 2013 7:51:17 GMT -8
What kind of wood Bob? I've used Home Depot cedar and Pine. No warpage but some of the Pine cuts real crappy. Some quotes from the thread, read through the rest at the link. www.cnczone.com/forums/woodworking/77860-wood_warping_after_milling.htmlI have had this happen many times over the years.
The problem is in the moisture content of the material. the more material you remove the more area is exposed for moisture evaperation. This causes the uneven contraction resulting in the cupping.
As was decribed before try to keep the material in a controled enviroment while machining.
When cupping occurs you can wet the opposite side with a damp cloth and place under a Heat lamp or set it in the sun and have a cup of coffee while you watch it strighten out.
The heat lamp and the sun accelerates the outgasing of the moisture causing the wood grain (pulp wood) to contract.
When the board is nearly flat clamp it to a flat surface and allow it to dry naturaly in a controled temp and humidity.
You can prove what I am explaining by finding a warped board weting the surface opposit the cupping and set it in the sun. If you let it set in the sun to long it will cup in the opposite direction.
It is amazing how much wood will move as it dries out.
...
The problem you are experiencing is from the depth of the cuts on the face, while there are no cuts on the back. The cuts on the front of the piece are relieving the stress on the face of the piece, while there is no stress relief on that back.
Go look at door casing, door trim or baseboard. You will note that on the back there has been material removed; on baseboard it is about 3/16" deep and about 2' wide on a 2 1/4" to 3" wide trim.
Try this: After making the design on the front, flip the piece over and route two concentric circles on the back. Make one as large as possible, and the one inside it about half-way between the larger circle and the center of the circles. Make the cuts on the back the same depth as those on the front.
...
Sometimes, even if your board is kiln dried, if your cutting and generating heat, the surface you are cutting will be drier than the rest of the wood, which may cause it to move. That, along with the internal stresses of wood as mentioned.
The opposite could also be true. The kiln was set too high, so the wood essentially is case-hardened, and wetter on the outside.
If you look at wide solid wood moldings, they'll often mill grooves or flutes on the back side to help alleviate this problem. If your piece won't be seen on the back, you can mill a relief to "balance" the piece, otherwise you might want to leave the piece thicker, and then mill the back side as well (flat)... |
|
|
|
Post by Greg on Apr 11, 2013 8:24:57 GMT -8
I found that any boards with knots in them warp the worst and the more knots the worse the warpage, the "A" grade boards I bought were knot free, every board I cut before getting these would warp and I would place an ammo box on top of the board inside my house and let it sit a week that wuld fix the board but it was a pain.
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Apr 11, 2013 19:06:24 GMT -8
I have been getting good results by clamping the wood to bring it back in line and letting it sit for a few days. As far as wood species I am pretty much done with pine, unless the bit is brand spanking new, I seem to get a fuzzy surface which on the detail I am carving is a real pain to sand out. What I have been buying is american cherry, spalted maple, ambrosia maple, red maple, red cedar and poplar.
|
|
|
|
Post by Greg on Apr 11, 2013 21:07:21 GMT -8
try some oak when you get a chance.
|
|
|
|
Post by ianhansamu on Feb 25, 2016 21:56:43 GMT -8
how to buy oliver 1013 and sent to Indonesia. and is it true that it costs about 2000 dollars?
thanks before..this mesin support with alphacam or not?..thanks before on anything..
by ian..indonesia
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Feb 26, 2016 11:59:44 GMT -8
Ian, note that you have to pay attention to the voltages also, the USA is normally 110V and many overseas countries operate at 220V. These machines are actually manufactured in Taiwan, it would obviously be less expensive for you to have it shipped factory direct to Indonesia. Normally these 1013 machines are available at around $2100 USA, not sure what they'd cost with 220V. Please contact Oliver Machinery directly at info@olivermachinery.net and they will be glad to help you with the pertinent facts and how best to proceed. Good luck to you with this, I've had my machine now for three years and have been pretty pleased overall with the performance and ease.
|
|
