Narrower Scrapers for Smaller Bowls?

[Randy Heinemann]

I have been using a 1" wide round head scraper for the insides of bowls but, on the inside of smaller bowls, the scraper is "grabbed" by the bowl.

Is the cause of this -

1. Whether the scraper is angled up, down, or level? OR
2. The scraper being too wide? Would a narrower scraper make this less likely?
3. Some other cause I just don't know about (since I haven't been turning that long)?

I am aware of negative rake scrapers and their potential advantages. For this post, though, I'm only interested in understanding why my round scraper catches lightly sometimes on the inside of small bowls. By small I mean 3" - 4" diameter bowls.

[William C Rogers]

A picture of your scraper would help. 1" is too big for a 4" bowl IMO. I use a 5/8" hook scraper for smaller bowls. Without seeing the scraper you could be catching the side, no downward angle, or not enough support.

[Brice Rogers]

Randy,

What makes a scraper grabby or catchy can depend on several things including:
1. Type of wood
2. positioning of the scraper
3. over-hang over tool post
4. Amount of tool doing actual cutting

Positioning - I've read that a scraper is usually supposed to be presented flat or with the rear of the handle up a little (tip down a little). They get grabby if handle is too low. On the inside of a bowl, it is best to have to scraper make contact slightly above the centerline of the piece. Reason? if it starts to grab, the downward force would pull the tool out of the cut if you are above center and will pull the tool deeper into the cut if below center.

Overhang - the closer you can get the tool rest to the wood, the less grabby it will be. On a bowl, you may find it helpful to make or buy a curved tool rest.

Amount of cutting surface presented. In general, the narrower the cutting surface, the easier it is to keep it from grabbing. A 1" wide scraper is probably too wide for any smaller bowl. If more than half of the cutting surface is in actual contact with the wood, you are starting to "tempt fate".

Sometimes if I am getting a scraper to be too grabby, I'll switch over to a newly sharpened negative rake scraper. They are HARD to get to grab.

Good luck.

[John K Jordan]

Amount of cutting surface presented. In general, the narrower the cutting surface, the easier it is to keep it from grabbing. A 1" wide scraper is probably too wide for any smaller bowl. If more than half of the cutting surface is in actual contact with the wood, you are starting to "tempt fate".


It is also a matter of the radius of the curve on the end of the scraper that determines how much edge is in contact with the work at one tome. For a 1" scraper the radius could be as short as 1/2" but that's unlikely, most are ground with a much longer radius. When I used such scrapers on smaller things I think I used a 1/2" round-nose scraper a lot. I generally use different tools now.

JKJ

[Michael Mills]

Only in my experience, normally caused from not having the tool angled down.
You do not say but is the bowl in standard "bowl orientation"? If it is in spindle orientation where you are trying to cut into endgrain it can be a real bugger.
I have 1/2" square scrapers made from HHS with 5% colbalt which work well for me for smaller items (usually boxes). The 1/2" thick gives the same rigidity as 1/4" thick and 1" wide, maybe more. Using a square hole sleeve you can profile each end differently.

[Peter Blair]

You might consider regrinding to a negative Rake using One of, if not the best, bowl turner in the world suggested 33 degrees both sides unless scraping a harder wood where he uses 66 and 33 producing a much more blunt scraping edge.

[Randy Heinemann]

Thanks for the info. I used the 1/2” last night with much more success. Also used the 1” scraper paying more attention to presentation. Both worked well. Probably will keep the 1/2” round scraper for tighter areas. Mainly just wanted to confirm that the grabbing could be due to too much of the 1” scraper’s edge making contact because of the shallower radius.

[Joe Kaufman]

You could try making small scrapers from 1/4 x 1/2 x 6" M-2 Rectangular Tool Bits. They are available from several tool companies such as KBCTools for about $7.50 each. You an grind a profile on each end and find out what works well for you. I use them w/o a handle when overhang does not exceed 3/4" or so. I find it most useful to grind a decreasing radius curve so I can limit the cutting surface engagement to about 1/8".

[Reed Gray]

Randy, maybe this will help... I put it up a couple of weeks ago...

https://www.youtube.com/watch?v=T4MKTOutZ3w&t=18s

robo hippy

[Peter Blair]

Looks as if I should have mentioned that Glenn Lucas is the turner I referred to. His demo was very good!!

[JohnC Lucas]

If it's grabby grind it to a negative rake. Make sure the total angle is less than 90 degrees so it will raise a good burr. Us the tool at or above the center line but the handle needs to be higher than the cutting edge. If it's not a negative rake this higher handle angle is really important. If it's negative rake and you keep the handle more or less parallel to the floor the negative rake will take care of the downward edge cutting angle. The more you have hanging over the tool rest the more grabby it will be. Take light cuts until you get a feel for how it cuts. Then you can be a little more aggressive if needed. I use a 1" round nose scraper for most of my work if I need a scraper. I do grind over the left edge so there isn't a sharp corner. Most new scrapers come with 2 sharp corners on the edge of the grind and I take these off by grinding further around. The sharp corners can dig in.

[Randy Heinemann]

Reed,
Great video. I doubt I would take my scraper use as far as you, but the information was very useful to me.