Shaping Foam

[lastchance]

Scenario:
I have my foam attached to an upholstery needle which is chucked in my dremel. I'm using an emery board to shape.


Question:

On some bodies I'm developing a crease while shaping. Does this mean I'm using too high of a speed? I'm thinking the heat generated, along with too much pressure from me, is cause this.

Or, do I need to switch to a finer sandpaper?

Thanks,
Bruce

[aged_sage]

Bruce...

A photo of the "crease" would be helpful. I do mine a bit differently from most. I first glue the body to the hook, and THEN shaped it with my Dremel. I glue strips of 400-1,000 grit sandpaper to the old sanding drums made for Dremel, after the old grit has been worn off through other applications. Consequently, I have not seen what you are asking about.

However, I am going to venture a guess as to the cause. I highly suspect that you are not holding the emory board absolutely flat, and that on occasion, the edge of the board comes into contact with the spinning body. This will definitely cut a 'groove', or "crease" in it.

Hopefully, this is the cause.

Regards,
Frank

[James Smith]

Bruce,

I'm not really sure what you mean by a crease. Perhaps you could post a photo of an example for us to see. For me, Emory boards with a light touch work fine. If I want to get a cupped face for a popper, I use one of those very small curved files that are about 7 inches long. They usually sell them in a set of 5 or 6 different shaped files. The Dremel I use is a variable speed model with a slifing switch so I can determine exactky how fast it is turning. My guess would be it's turning at around 4-5K RPM. Perhaps you're applying too much pressure causing the foam to heat up and melt?

Jim Smith

[lastchance]

Jim. Frank. I'll try and get a picture up today. Jim may have hit on it, though, maybe it's turning too fast and I putting too much pressure on it.
Bruce

[aged_sage]

Personally, I seriously doubt that it is turning too fast. In my experience, it is either too much pressure, or, as previously noted, letting and edge of the emery board touch the foam. The edge of the board can cause a lot of 'damage' if it comes into contact with the body. This is why I use the tools that I do. The circular drum does not pose the level of edge exposure risk of an emery board. This is NOT to say that using my technique one never messes up a body. (Don't ask me how I know!) I just seem to have much better control of things doing it the way I do. It DOES require a 'light touch' to keep from messing up.

Should you opt to try my method, there is one major CAUTION: DO NOT HOLD the hook in your hand. Use something like a small pair of Vice-Grip pliers, or heavy duty Hemostats. The first 2-4 bugs held by hand goes quite well. HOWEVER, you unwittingly begin to hold them with less and less pressure. Finally, the grit will 'catch' one and throw it all around the room. I once spent three days looking for one!

[lastchance]

Hi Aged Sage. I tried a couple holding the foam and it seemed a lot more diffiuclt for me to shape it.

[aged_sage]

Hi Bruce...

Clearly, what works best for you is how you should do it. You are to be commended for at least trying 'something new'; most won't do it.

I hope you did use a much finer grit sandpaper on the drums than comes on them. The "Factory" installed grit WILL NOT WORK. I have found 320 grit to be too coarse for good work, and the standard drums have either 80 or 120 grit on them---disasters!

Cheers!
Frank

[lastchance]

Hi Bruce...

Clearly, what works best for you is how you should do it. You are to be commended for at least trying 'something new'; most won't do it.

I hope you did use a much finer grit sandpaper on the drums than comes on them. The "Factory" installed grit WILL NOT WORK. I have found 320 grit to be too coarse for good work, and the standard drums have either 80 or 120 grit on them---disasters!

Cheers!
Frank

Hi Frank, what grit sandpaper do you recommend? Dremel doesn't offer anything real fine.

[Fishingfiend]

Something else about using an inexpensive sandpaper or emery board. Pieces of the grit "break off" and can roll, stick or cut the foam in ways that don't result in what you want.

[aged_sage]

last chance...

Yeah,I know. Why do you think I started saving the little cardboard drums after all of the 'factory' grit had been worn off? (I have been accused of being a hoarder.) A fresh sandpaper strip does NOT glue well to a drum with fresh 'factory' grit o nit!! Incidentally, if anyone has some of the drums with most of the grit worn off, I will gladly receive any and all contributions to the cause. I will even reimburse for postage. (I provide the 'converted drums for our clubs foam tying class every year, and can always use more than I currently have.)

Nothing any coarser than 400. I often use 1,000 grit. At least, up to this grit, everything seems to work better than the previous coarser grit. I have grits to 2,000 for sharpening hand plane blades, but don't feel that one needs anything finer than 1,000. The finer the grit, the 'softer' (to coin a term) the cut and the easier it is to control. If the grit is too coarse, you can spend more time 'fighting' the foam than warranted. The coarse grits not only make rough cuts, but the also 'bite' into the foam, making it difficult to control things. It is amazing at just how fast the finest grits I have used cut the foam down to shape. Having also used the extremely fine grits for polishing turned reel seat inserts, where it is next to impossible to detect any changes at all, using them on foam was a real eye-opener

My suggestion is to buy a sheet each of 400, 600, 800, and 1000. The height of the cardboard drums is 1/2" (at least for a Dremel). Measure off, and cut 1/2" strips for 'stock'. Cut each strip to length from the stock strips, and glue them to the drums using a good contact cement. Let them 'cure' at least overnight (guess how I learned this trick!). Using a drum covered with each of these grits will enable you to decide for yourself which one(s) work best for you.

Regards.
Frank