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Vacuum not enough?10/8/14
please give an opinion as why parts not holding.
Assuming that your tooling is in good shape, can you describe your cutting strategy? Are you using an onion skin method on your small parts, or a return onion skin? How about cutting order? Try to arrange cutting order so that the part is connected to as much panel as possible before being cut free. In other words, you don't want the part already separated from the nest while removing an onion skin. Can you post code so one of us can take a look at what you are doing. Also, what tool is doing the work. Also software generating the code. Some cabinet packages do a horrible job with start points and cutting order. I won't name them, but they know who they are.
I have to use a Part cut strategy as I have a 15 hp regen, does a great job and unless I want to add more I cut small parts first (most vac) and onion skin to .03 then all cut thru on last pass, yes time is money but so is a Vacuum !!
you could add one and spilt your zones
10 hp on a 4x8 doesn't seem like a lot of pump to begin with.
Are you cutting your small parts in two pecks down ( say leave 1/32" for the final pass) ?
Are you cutting the little pieces first on the sheet then the bigger stuff?
Is your tooling sharp?
Are you using downspiral bits on small stuff?
Make sure the bottom side of the sheet to be cut is clean with no dust on it.
Worse comes to worse on tiny problem parts you can "onion skin" as the other post said. Leave 1/64" or a little less in the depth, break the parts apart and trim them with a trim router by hand.
When you pull the valve out to take the parts off, what does the gauge read? What is the pressure when it is closed ?
When you go to remove your parts and pull out the handle you are closing the valve and your pump should read the maximum pressure that the pump can produce.
Now push the handle in and open the valve and compare that pressure. This should tell you how much pressure you are losing. Due to spoil board and gasket vacuum loss.
apply packing tape around the permeter of you spoil board and see if the pressure increases. that will determine if your gasket is leaking.
Next seal the edge of your spoilboard with wood glue.
One more test, cover the whole spoil board and edge with plastic and look at the pressure.
Next, what material are you using for the Spoil Board. I personally do not use the ultra lite board for this.
As fall is coming on and the heat in the shop is turned on I've seen spoil boards warp and curl up around the edges to the point they will not seal.
I use a 18 Hp Becker on my 5 x 10 table seldom ever, have a problem and when I do, I follow the above procedure to determine the cause.
Good Luck Will
We have 2 10hp pumps on a 4 x 8 table and we get over 20 on the gauge. If I saw 15 I would be concerned so yes I believe you do not have enough.
The 18 hp Becker is designed to hold 22 inches all day so when I see 15 on my gauge I know I'm losing vacuum somewhere
Thank you for all responses,
You might want to try ultralite MDF like Trupan for your spoilboard.
10 hp should be more than enough if you are cutting laminate cabinets.
do you have a picture of your nest?
What size are your small parts? Are you cutting full sheets and having problems?
most of the flying parts are nailers or stretchers ( 3 to 4") width
We bought a Woodtron some time back and had terrible problems with small pieces. It came with a crappy 80mm 3 blade cutter for surface planning that never really gave a great finish. I used a 6 blade diamond tip, 100mm tool we use on our Biesse to see if it made a difference and the quality of finish was vastly superior. We've since gone to an 8 blade 130mm diamond tip. Same great quality surface but planes faster. We now only lose the smallest of pieces.
Put the start point near where the arrows in the image are, in the order specified, and even at 15inches of mercury, you should be able to hold those parts if you do a return onion skin and your chip load is reasonable.
I have the exact same machine with 10 hp pump. Yes there are times I wish I had more. They do have the machine ready with the wiring and controls for a second pump on mine. Onion skin will solve a lot of your problems. We have cabinetvision so it automatically skins narrow pieces first and then cuts before larger pieces. It has made a huge difference and very little slippage. Had machine since 2007 and always used a 1/2 " spoil board.
Akram, if you always make those parts in pairs you can tab them together.
We make very small parts and pair them that way. I just leave a .03 skin between them with a 1/2" of material plowed out. and then we have a small router table on the out feed table with a 3/8 flush trim bit.
My guess is that you are getting more them 15 with a full sheet and as you cut and create leaks its drops. Another/more pump will just allow you to overcome more leakage. I would get a new gauge from Mcmaster and mount it remotely where it is easier to see, that is what we did. I started with 10hp and doubled it to 20. If you can swing more pump it is worth it. Between the time and material for remakes it made sense for my operation.
What is your altitude, this has a direct affect on how much vacuum you can pull. If your at 3500 ft or higher you probably need more vacuum.
CFM for air flow and PSI for small parts. There is no reason for your CNC Router not to be able to cut finished parts in a single pass regardless of the size or quantity or substrate. Please contact me and let's see if we can't give you some assistance.