I'm Struggling with inside curves - tools and techniques - Help please

Col Defender

Col Defender

Joined
Nov 11, 2011
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Hi - here's a pic of some partially done blanks I'm working on now; the steel is 1084, not yet heat treated. I have been experimenting this morning trying to do a better (and quicker) job shaping the inside curves on the handles. Not going well!



Tools I have available are some round files, a right angle grinder, a drill press with a few small round grinding stones I can chuck into it and a dremel tool with round grinding stones. Also a 2x42 Sears belt sander. All this stuff works but it is all super slow and inefficient. Which sometimes causes me to want to accept "good enough" so I can move forward.

How do you guys do this? Technique with the tools I have? Some other tool that works better?

Thanks in advance!!

Steve
 
Thankfully I have a 2X72 belt sander that accepts small wheel attachments. This makes life easier, well at least it makes inside curve grinding easier. What you can do if you have the budget is get an oscillating spindle sander that uses various sizes of sanding drums. I found mine very helpful until I got the big boy toys. It shouldn't break the bank either.
 
Dremel with sanding drums (takes a steady hand) or chuck up the sanding drums in your drill press. Be careful with the drill press and lateral pressure. They arent made for that task, but work well for the task. Maybe a little slower, but efficient. The HF 1x30 works pretty well for inside curves off of its small top wheel as well. Just a couple other options that all have worked for me in the past and present.
 
i4Marc said:
Thankfully I have a 2X72 belt sander that accepts small wheel attachments. This makes life easier, well at least it makes inside curve grinding easier. What you can do if you have the budget is get an oscillating spindle sander that uses various sizes of sanding drums. I found mine very helpful until I got the big boy toys. It shouldn't break the bank either.
Click to expand...

Thank you i4Marc - I had to google "oscillating spindle sander" just to see what it is. :-) I guess the drum goes back and forth instead of all the way around???? And will this cut curves in 1084 steel? Thanks so much for your help.
 
Col,

The drum spins all the way around but in addition it also rises up and down. It will cut curves in 1084. The biggest issue with those spindle sanders is that the abrasive drums they use are AO (Aluminum Oxide). These are better suited for softer materials like wood but they will work for steel as well. They just wear out faster than abrasives designed for hogging out steel. But compared with hand sanding I'll take it any day. The best way to do it is to cut out as much material as you can with saws, grinders and files until you have the shape close then use the spindle sander to clean it up and make nice smooth curves. You don't want to rely on it to do all the heavy lifting, just the clean up. If you can find someplace that sells sanding drums with tougher abrasives then by all means get and use those. Shop around and get a spindle sander with the highest rated HP you can find within your budget. And buy the sanding drums in bulk if you can find them. Like I said, they wear out fast.
 
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Try some half-round files too. They'll remove more metal and make a smoother curve than round files.
Also try draw filing with them.
 
I'm assuming your using the right angle grinder to cut out your blanks. Do you make use of relief cuts for the inward curves?
 
half round files work great. Make sure they are sharp, and I use my daughters sidewalk chalk to chalk the files every so often. The chalk helps to remove the metal from the file teeth and keep it clean and cutting. Also have various round stock sanding blocks with sand paper.
 
you have a drill press already, so get some sanding drums in different sizes.
 
Thanks guys for all the suggestions!! I did pick up a half round file today and you guys are right; it works really well compared to other files I have used. The oscillating sander sounds like a great idea but if I can do the job without that expense I will try to do without. But new tools are always nice! :D
 
I've only made a couple knives, so I'm no expert; but I've made that inside curve on mine pretty easy using a bench grinder with a regular stone wheel, carefully grinding it on the corner of the stone till its almost the perfect curve I want, then finishing it out with 120 grit sandpaper then finer grit till its all smooth. Its a bit quicker than files for me, and I wanted a tighter curve than my half round file. I would think you could use your belt sander the same way, maybe on the top wheel if you can get to it and if its the right size for your curve
 
Ditto on the half round! Then get another half round. Chainsaw file to draw file and put a better finish before sanding. ***tip cut a chainsaw file in half and golf ball handles on either end*** then sand.. Watch the dremel you'll make ripples in record time. Scribing a known radius helps if it is not going to be a compound radius. Trying to stay cheap for ya...
 
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