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Thread: Cutting thick felt
02-27-2012, 04:14 PM #1
Cutting thick felt
I need to cut out round pucks of felt with tapered sides, truncated cones 1/8" to 3/4" thick and 2" to 4" in diameter. The side angle is about 6 degrees, but may vary as the design unfolds. Obviously, punching is out. Laser cutting is a possibility if it gets into quantity production, but now I need a variable process i can use as needed without waiting for delivery. Current thinking is to put a dull blade on the DoAll and hold a grinder on it to make it into a razor blade, then mount an appropriate disk on a gearhead motor to rotate the felt past it. The disk could have needle points to stick the felt on and the blade direction would be holding the felt down against it. Dust generating methods such as grinding would not be desirable.
02-27-2012, 04:24 PM #2
Maybe you could adapt one of the electric upholstery foam and material cutting knives that use a reciprocating blade and are mounted on a stand to cut angles.
02-27-2012, 04:27 PM #3
What about using some nichrome wire and a variable transformer to make a hot knife?
You could build a stationary hot knife with a Velcro turntable. Slap your rough cut blank on the turntable and give it a turn. It would make a ton of smoke.
02-27-2012, 04:30 PM #4
I have experience with this. results depend on the type of felt, wool, polyester, etc and grades, there are many.
I would probably want to punch to make a blank, but you may be able to start with a square.
a band saw is one way, you can buy razor edge blades anywhere you get regular blades, they are extremely sharp.
your basic idea of rotating at an angle is good, the pins can be agumented with a top hold down plate.
you may find that the blade dulls quickly, if so, you can add a sharpeing stone like on a skiver that sharpens the blade continuously. Foam is shaped this way also. I had project where I was beveling the edge of 3/4 inch thick pu foam die cut to an irregular shape. I set up a band saw with a tilted table and ran a razor blade at 5500 fpm. the foam was fixtured and the operator just ran it around and it sliced off like magic.
leather skivers are hori band saws that runs 2 inch wide blades with enormous tension on them and continuous hollow grinding. Skivers can split leather to paper thin all day long. I have seen them used to contour split foam, felt, and leather, a common opperation in footwear mfg.
The other way of forming felt is with a belt grinder, this depends on the exact materials and shapes and desired surface. I had a part I was making a year or so ago in a small test run where I held the felt in a form so it would not move and shaped it with a 36 grit belt and it worked very well.
use good dust collection!
digger doug liked this post
02-27-2012, 04:47 PM #5
i once had to make a few 1/2" thick felt disks with someting like a 20 deg. bevel on the edge...nothing all too accurate. stacked a rough cut blank between two metal disks with a long bolt and nut through the center...chucked it in a drill and hooked up to the longest extension cord i had in order to get way outside the shop....then i had at it with an angle grinder with a 40 grit abrasive pad. just remembering it makes me want to go into a sneezing fit.
this was with real wool felt, i imagine the synthetic stuff might melt a bit.
adama liked this post
02-27-2012, 04:49 PM #6
As with Mr. SJ, I also have some experience with this. If you want a textile dedicated band saw for the project, my liquidator that I use has them cheap. Double Check, but I belive that the table is adjustable by angle.
Current sales flyer second page in the middle
T&T Liquidators and Auction Company, Current sales flyer
If price is an issue on the equipment look at something like this:
65mm Blade Electric Cloth Cutter Fabric Cutting Machine 220V | eBay
You can remove the bottom plate and make a permanent holding bracket at the angle you want. I have even seen these hand held units adapted into automated cutters.
02-27-2012, 04:57 PM #7
02-27-2012, 07:06 PM #8
jason. you can pattern skive leather, foam etc. a relief plate is made and the material is pushed into with the top pressure rolls and the blade cuts straight, when the pressure is taken off, you have the negative. It would not do this type of bevel.
BTW, I could see doing this on a lathe, maybe using one of the circular cloth cutters suggested by Jason.
I could see where one of those may work in place of the band saw also, especially if it has a sharpener.
02-27-2012, 07:40 PM #9
02-27-2012, 08:25 PM #10
Each year my high school English literature teacher would assign a composition on whatever the students liked to do or were interested in. He said he was always amazed at how much more a bunch of high school juniors knew in aggregate than he did. About the time you get to thinking you know your way around, you run into something like the list of machines for sale. I don't even have an idea what some of them do, like stepping into a different world.
Since I have a band saw with a tilting table and a few gearhead motors around, that is what I will do to begin with. I would be delighted for this to get to where I needed a dedicated machine, but it is all speculation and experimentation right now. Just so I am not keeping everyone in suspense, i am working on a different way to apply a French polish. Results so far have been outstanding and I am now trying to get it into a marketable form, which is much more work than making and testing the first prototypes.
Thanks for a lot of great advice, and I will make sure I don't get in the way of a razor band at 5500 fpm. Just typing that is scary.
02-28-2012, 05:50 AM #11
You don't say how many you need, but if it is a small order, I was thinking you could use a lathe. Turn down 2 sets of aluminum plates 2" and 4" with the inner plate with your 6 deg on it and drill and countersink flat head 1/2 diam flat head bolts in them put hex head nuts on the back side to hold in the bolts. Then chuck one up in a 3 jaw chuck cut a piece of felt slightly bigger then you need with a scissors or snips, put the other plate in the tailstock and squish the felt between centers. If it slips, roughen the surfaces of plates, then put a razor thin sharp utility blade in a parting tool and turn your compound to 6 deg. and cut the felt. It might take some trial and error to get the process down, but I bet that would work. Just an idea from an old fart problem solver...lol.....
02-28-2012, 06:31 AM #12
I'll be interested to hear about your product. I was french polishing samples last week. Have a different one to do this morning, but waiting to hear (hopefully soon) when they want to call the meeting as to whether to go ahead and do it, or just take it in the white....
I don't know how rigid you are on exactly 6° and (absolutely straight?) sides. But I would experiment with a wooden or UHMP form with a slight cone up in the center. Rough cut or punch the pucks round and slightly oversize, drape on the cone with a hollow hold-down, and punch again with on size punch.
Should have taper sides when flat, maybe slightly hollow or rounded. The edge effect (rounded or hollow) can be slightly modified by whether the taper on the punch is inside, outside, or centered. Also, whether the part is punched hollow below (small dia will be up); or cone below (large dia will be up).
Richard King liked this post
02-28-2012, 06:31 AM #13
Soak em, freeze em, take em to the bandsaw.
Last edited by <jbc>; 02-28-2012 at 06:44 AM. Reason: maybe you know a butcher?
02-28-2012, 06:38 AM #14
I wouldnt worry about the 5500 FPM, I did that to cut the foam and that is what I was able to juice the drive up to. what kind of felt are you working with?
02-28-2012, 08:12 AM #15
OK, to more or less answer, there is no order size, this is strictly a prototype situation right now. The 6 degrees is what looked about right on an Autocad drawing and is subject to change at ay time. It is just a matter of backing off the side to allow working into corners. I'm sure freezing and sawing would work, but knife type cutting methods are attractive from the low dust aspect.
As to history and applications, a while back I found myself working outside of my normal areas of expertise, (whatever that is) and was expected to French polish things like 12' pine planks. The methodology was even more primitive than the old mittens dipped in paint and smeared on cars. What made it really bizarre was that I have a positive pressure spray room with filtered incoming air and good spray equipment that I was not allowed to use because it couldn't be called French polishing. After following orders for a few days, I concluded that the only way to finish the project in a lifetime was to reactivate the slave trade or develop a better method. I made three applicators and found that not only did it speed things up immensely, the unintended consequences were almost all positive.
Right now, I am working on putting together the kit that will cover most shapes and uses. I think the two main targets are people like luthiers who want a very controllable fine finish and home shop woodworkers who do not have access to dust free spray rooms and have the patience to spread the work over a number of days. The finishes i was getting without rubbing out, just as applied, were so tactile that every day as I walked down the isle to my work area, I had to slide my fingers along the finished boards stacked there.
SJ, I am using medium hardness felt from McMaster-Carr. I am not far enough along to be looking at wholesalers.
Steven Thomas, if you are going to be finishing on a regular basis, I could use a beta tester. My PM box is always full, so you can reach me at [email protected]
03-02-2012, 10:22 PM #16
I detest finishing of any sort, but tend to like french polish for some projects because it is easy to do or touch up on site. Also for re-finishing old stuff. Like you, i sometimes have to use if for "historical authenticity" It certainly is (as you note) a wonderfully tactile finish. I tned to either spray conversion varnish, or use shellac/french polish. Not much in between.
Shellac is preferred for low impact on me, too, though it is a workout on aging joints. Even there I am not convinced a day holding a spray gun at arms length is much better. though the coverage rate is much much faster.
I have the end of a small room to do over the next couple months, bunch of shelving around a small entertainment area. (bigger than an "entertainment center"; much to small to be called a home theatre )
So will email you next week about testing the product.
03-03-2012, 07:22 AM #17
in regards to felt. I would assume you want to use wool felt, but there are felts made from every fiber imaginable and some wool felts may have other materials in them, like polyester. McCarr has a pretty good run down on the different grades.
There are some cheap felts that are 100% recycled fibers, like recycled clothing, these used to be used alot for automotive sound absorbtion.
03-03-2012, 09:38 AM #18
i do like the idea of a die type cutter with a dome under the material,,it would be the least dust.repeatability would be good too.
03-03-2012, 12:59 PM #19
As I said earlier, the design is "fluid", changing almost daily. The latest felt pieces have a much steeper taper.