Holding Things Down

I cannot believe I missed the entire month of August! That just goes to show you how busy the ShopBot has been this past month. Now let’s get down to what was going on…

After the last article, I moved from using a high vacuum low volume pump to a single Fein Turbo III shop vacuum. This vacuum gave me a lot more cubic feet per minute of air flow but at the cost of much lower vacuum in inches of mercury. I was trying to spread this vacuum over the entire 4’x8′ bed of my machine to boot. The lure of holding full sheets of 3/4″ plywood was just too much for me to resist. I had to try it.

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My first impressions were good, and the holding power was much more than I expected. I was cutting cabinet parts for another shop and the job would stay put till I turned off the vacuum. After cutting several jobs, I got the job that was going to burst my bubble, put me back at ground zero and cause everything to stop in the shop… Or at least I thought it would. I received a load of the most bowed ply I had ever seen. I had used Zebra Wood in the past, but never Rainbow Wood! Vacuum would not hold this twisted mess no matter how I pushed or pulled it. Screws was the only way to tame this beast. My bleeder board is still new and I didn’t have a bunch of holes in it so driving that first screw was like getting that first scratch on your first brand new car. After getting the job out of the door and surviving the screw holes I started to think if only I had a little more CFM, I might be able to get that ply to suck down……..

2_2vac Next comes the second Fein Turbo III and a “T” installed in the manifold for both vacuums to connect to. I like the built-in feature on the Turbo III that will switch the vacuum on when a power tool that is plugged into it is turned on. With this feature, I connected the second Turbo III to the first one so I only had to switch one of them on and off. Works like a charm. Oh, I forgot to let you know that I tried a Sears Shopvac with the Turbo III before I bought the second one. In short, the Fein could produce more vacuum than the Sears so as hard as the Sears might try, the Fein caused the exhaust port on the Sears to suck air back into the system. In effect, the Sears was causing a big leak!

Now that I have all of this air flow, but no more vacuum as in inches of mercury I am ready to tackle that next load of Rainbow Ply. Well to date I have not gotten another sheet bowed like the others so I cannot comment on just how much better things are now with two Feins under the table. I can say that my cutting boards do hold a lot better. I am now laying the blanks directly on the spoilboard and cutting them right there. I learned the hard way that you must keep the debris cleaned from under the blanks or it will act just like small ball bearings and cause the blank to move around under the load of the bit.

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After a quick visit to Bill Young’s shop and seeing how he uses Baltic Birch to make a vacuum mask with gasketing, I had to try this for my setup. Let me tell you this, there has never been a happier ShopBotter anywhere than after I got my first mask with gasketing up and running! That is so slick and so easy to make, use and maintain. You have got to try it if you ever want to hold parts tight with a little vacuum. So you ask, how did I do this? I took a 49″ by 60″ 1/4″ Baltic Birch panel and laid it on the bleeder board (spoilboard) I made sure the X and Y zero was exactly matched up with the corner, Lower Left on my machine. I then turned on the two Feins and that sucked the 1/4″ ply down real tight. I then created a part file that would only cut into my 1/4″ ply .0625″ exactly where my outside profile cut would be for all my boards. Next I offset to the inside by .75″ and cut the center out, all the way through. After this, I placed AllStar gasketing material just inside of the first profile cut but keeping it away from the center cut out. This way I was creating a vacuum chamber under most of my cutting board blank. I had a few blanks that were made from White Oak that had worm holes in them and a knot or two thrown off to the side. They would not suck down to the table and stay put. There were just too many air leaks in these blanks. With the vacuum mask and gasketing, these “dogs” stuck so tight I was able to cut them out at twice the speed I normally cut my boards and they didn’t move. In short, if you don’t like screws you will love 1/4″ ply (or other materials) and gasketing coupled with a good vacuum cleaner for holding parts. I have never had the pleasure to use a Roots Regen Blower so I don’t know how nice that might be, but for this little shop, two Fein Turbo III’s and some AllStar Gasketing will take me far with holding my parts in place!

2boards One other thing I want to say about my cut quality is that holding parts tight will make a big difference in the quality of the cut. The other is changing from a .25″ bit to a .375″ bit, WOW what a difference.

Last article I said I was trying out some new design software and I might say a thing or two about it this time, so here is a quick update. I am using V-Carve PRO ver. 3.1 for my design and toolpathing software. I find nothing better for me, in this price range for making signs and general parts. You owe it to yourself to at least look at this software package. I have also been using Corel X3 for more design work and exporting either an .eps or a .dxf file and importing that into V-Carve PRO. I already had the Corel package since that is the standard for laser engraver folks. Just today I designed a plaque in Corel, exported the vectors, cut the plaques on the Shopbot and then brought the plaque to the laser for engraving.

Till next month, here’s wishing you parts held tight, sharp tooling and good business.


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