vac vs shop-vac

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MadRussian
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vac vs shop-vac

Post by MadRussian »

I'm building router profiler and decided to go with a vacuum to hold core down while machined. I bought a decent size vacuum pump and now I'm not really sure what better vacuum or shop-vac for my needs.
Vacuum pump can build vacuum up to -15 -psi may be more. Is that enough? Because suction at pump inlet while it's running not that great.
do I going to right direction? little bit confused here :oops: need some help.
sammer
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Post by sammer »

Both will work.
Depending on the volume of air you have to move one might work better than the other.
Shop vacs move a lot more air but develop little real vacuum.
Vacuum pumps move a lot less (air 3 to 5 cfm's is average for a decent sized vacuum pump) but really suck.
So I guess what I'm sayin' is if you have lots of channels and holes to pull air from or lots of open holes shop vac might be the way to go.
Vacuum pump will still do it, might take a few seconds longer to create vacuum but ultimately will have a stronger pull once sealed (It will have to be sealed)

Hope this makes sense.

sam
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twizzstyle
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Post by twizzstyle »

A vacuum pump will pull a stronger vacuum, however the flow rate is SLOW compared to a shop vac. If you have a leak proof system a vacuum pump will work ok it'll just take a little bit for it to build vacuum, but if there are any leaks you'll get basically nothing. A shop vac just has a might higher flow rate so it can over come any leakage. But a shop vac isn't meant to run for long periods of time, like a vacuum pump is.
MadRussian
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Post by MadRussian »

sammer wrote:Both will work.
Depending on the volume of air you have to move one might work better than the other.
Shop vacs move a lot more air but develop little real vacuum.
Vacuum pumps move a lot less (air 3 to 5 cfm's is average for a decent sized vacuum pump) but really suck.
So I guess what I'm sayin' is if you have lots of channels and holes to pull air from or lots of open holes shop vac might be the way to go.
Vacuum pump will still do it, might take a few seconds longer to create vacuum but ultimately will have a stronger pull once sealed (It will have to be sealed)

Hope this makes sense.

sam

my pump 6 cfm I suppose this is good. Can you explain on sealing part. ...rubber sheet as a gasket with holes on all table? Thin sheet of soft foam under core ?
sammer
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Post by sammer »

If your table is full of holes and your cores are only covering half of them you'll have to find a way to cover (seal) the rest.
If your core isn't flat or has grooves etc that will allow the vacuum to leak it wont hold very well.
I've yet to build a vacuum table so maybe someone who has can elaborate.

sam
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falls
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Post by falls »

I remember iggy made an elaborate setup for their vacuum hold down base cutting jigs using a vaccuum pump and tubing. I'm pretty sure they abandoned it for shopvacs. I think it will be hard to create a really good seal between 2 pieces of wood that isn't prone to perhaps uneven pressure, which would affect the accuracy of your final thicknesses after routering.
I'd think a shopvac would be best, but I don't know for sure.
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sir.orange
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Post by sir.orange »

below you see my vacuum set-up for routing cores and sanding them. i started with a normal vac-cleaner like everyone has. by chance i got a festo vac, industrial quality, the core-hold is a little tighter, but both works fine.

im doubting that you will succeed with a vac-pump, without spending a lot of money in a propper table set-up with channels below the cover and sealing. ( how much power/watts and volume does your vac-pump achieve??2500l/min is minimum i think)
the less air the tool sucks, the better must be the sealing

the volume and power of a strong vac-cleaner (something like 1500w 3000l/min) upwards should be an effective, cheap solution.



its a 19mm mdf-plate with channels (1-2mm deep) and 3 holes where the vac-cleaner is connected. i did tests with plastics tables and routed channels in there, but i found out that the 2 surfaces (wood-core --- vac-table) works best having rough structures.

the channels aren t exactly alined the cores as i use this plate for all different cores i use in my skis. if the cores are too short to cover the channels, i cover the channels with tip-spacer material, and get the tight hold back. the rails are cnc machined out out off pp, every ski has its own rails.
i router the core down to 2mm at the tip and tails, and sand of 0,5mm with a belt sander (i do full-wood-core, thats why 1,5mm)

i have to look after the sidewalls. they must lay flat on the mdf-board. if they stick out because there s a channel below them, they start to flatter, and blow up right in my face :|

Image


the bridge. its 16/19mm plywood, with bearings to prevent wedging. the tooth bruches keep the rails clean, to work dimensionally stable. the router slides on the bridge, the next one will be attached fix. like kingswood does it. i also tried kingswood rail system for routing - pain in the ass. welding the srews sucked, i wasn t able to adjust anything correct, and the steel tubes bended while welding. just to warn you...
the wooden bridge-frame that keeps the router in place on the bridge has !?notches!? because i had problems with shavings that pinched the router.

now that thing works great and is my way to got for full lenght wood-cores, unless i have a cnc ;)
i need something like 2-3 hours for a pair of cores. could be faster i know, but thats ok for me.

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Jibber
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Post by Jibber »

I power my vacuum table (http://www.raget.li/?p=42) with a normal vaccum cleaner (1500W). It is a box with one big hole to "connect" the vac. The top has a grid of small holes (<2mm). I cover the area which is not used with scrap wood the get a better vacuum. Works perfect for me.

Cheers, Christoph
MadRussian
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Post by MadRussian »

Looks like I'm going to have to rethink how to secure core into profiler and go with shop-vac or maybe even leaf-blower.
Can vacuum pump be used for something else in ski building?

If I have time maybe will try small-scale with vacuum pump just to see what happened only because I read you have a pump.

how could I missed it on 1:23 in kingswood video you can clearly see shop-vac attached to the table
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falls
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Post by falls »

vacc pump is useful for vacc bagging coreblocks
vacc bagging skis/boards if you don't have a press
for capping sidewalls in the tip while pneumatic pressing
many uses....
I suppose you could vacc bag your base material against a flat board for 24 hrs after you cut it off the roll to get it flat before cutting the ski shape out
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sir.orange
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Post by sir.orange »

MadRussian wrote: how could I missed it on 1:23 in kingswood video you can clearly see shop-vac attached to the table
by the way, he is using a heavy duty festo shop-vac (1200W max / 3900l/min / 24000 Pa pressure)
iggyskier
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Post by iggyskier »

Ridgid Shopvac from home depot. Lifetime warranty so just go in and swap it when the motor burns out.

I still have that nice vac pump if someone wants it to vacuum bag skis. Not sure why we haven't sold it yet. I will put it up for sale soon.

But yeah - my advice is go simple and cheap. Don't try to over complicate it.
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falls
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Post by falls »

hey iggy
looks like your latest vacc hold down has 2 spots where the vacuum "sucks"
did you make some other types with a central vacuum hole then end up with the double hole?
mine have a central vacchole and i find on long skis the suction at the ends is weak.
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falls
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Post by falls »

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Don't wait up, I'm off to kill Summer....
iggyskier
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Post by iggyskier »

falls wrote:hey iggy
looks like your latest vacc hold down has 2 spots where the vacuum "sucks"
did you make some other types with a central vacuum hole then end up with the double hole?
mine have a central vacchole and i find on long skis the suction at the ends is weak.
Maybe our first year we had some with one hole, but everything since has two. Our suction is pretty good. One thing that helps is deep channels. More airflow the better.
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