Slip Joint makers and FLAT pieces

Ryan Minchew

Well-Known Member
Hey guys, got a little time and wanted to ask a question. One of my biggest problems with slip joints is getting things flat really flat. I can flat sand on the grinder to get the scale off then take it a granite plate and get what I think is flat. When I put the mic to it I find other wise. THe leading points and spots through the blade and spring have high and low spots. This creates gaps between the spring and liner. Getting an almost seamless transition between my spring and liner it's a struggle in every sense of the word.

I've talked to Todd Davison, I've seen Tony Bose's tutorial and they both use the belt grinders to get them flat. I just can't seem to get it I still have gaps that I have to fight and fight and fight to get right. Do ya'll have any tips? What are you doing to creat no gaps almost seamless tranisitions between liners and springs?

I know most answer will be a surface grinder, but at the present time my 6ft by 8ft shop won't handle it. I was just hoping someone had a idea of what I might be doing wrong. Thanks for any help. Ryan Minchew
 

Chuck Gedraitis Knives

Well-Known Member
When you are sanding on the granite surface plate do you just go back and forth?
To get something flat you need to lap it in a figure eight motion.
Another trick to do when you are trying to flatten on your belt grinder is to paint the side you are grinding on with dykem or color it with a marker. Then grind a little and then look at the piece. You will see where you took off material and where you didn't.
 

Ryan Minchew

Well-Known Member
I've been doing the figure 8, but I think my problems are starting off on the grinder. Like possibly it's flat after the granite plate, but not parallel.

When I grind on the grinder my parts are already profiled. I start with a 120 grit belt and go from there. The main places that give me trouble are the areas like the end of the backspring that holds the last pin. It might be .002 thinner than where the middle pin goes, sometimes more. I've place with belt speed and tension, and it seems to make a difference for about a half a second then I'm back to square one.

ALso would I benefit from putting the knife together sans blade and reaming all the holes together at once?
 

Brent D. Cramer

Well-Known Member
First buy surfaced ground blade stock and only hand sand it with 400 grit or finer and Mic it often while sanding. As for the liners, I will lay them on the grinder using a fresh belt at a slow speed. Next how are you holding your parts to the platen? I found some two sided scotch tape the kind that Wal-Mart sells. It allows me to hold the part to the machine and turn it on and off without removingit from the machine. I also use it on the block while hand sanding. Lay a piece across the part spread your fingers apart to apply even pressure. I hope this helps.
 
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Frank Niro

KNIFE MAKER
Good to see you working with the knives a bit. And thanks for the boost on my folder.
You weren't having this problem before were you? It has sort of snuck up on you? I believe what your problem is due to a wear spot of some sort on your platten. What happens is the belt in fact takes a bit of a direction change. Get a straight edge out and perhaps a light. Of course if you have a glass overlay you probably can turn it over. Regards. Frank
 

Ryan Minchew

Well-Known Member
Thanks for the tips. I think starting with precision ground steel would be best, I just can't find it the steel and sizes I like. I like the tape idea.

Frank ya stranger, it has been a constant battle, sometimes it doesn't show up as bad. You are right though I do have a wear spot so I changed over to a new flat platen with the same results.

Anyone know where I can send 5 foot of steel to be precision ground.

Or another option I'd like your opinions on. I have limited shop space, but I could fit a table top mill in place of my drill press. Once parts are cut I could use the mill and a fly cutter to get em flat and parallel and use it as my drill. I'm not looking to do a lot of milling, I just need to remove a couple thousandths on each side evenly. I could do a couple thousandths on the grinder but its obsiously not working for me. Do you think is doable? Thanks again for the advice and tips.
 

Brent D. Cramer

Well-Known Member
Do you have a machine trades school close? Sometimes you can get the students to surface grind it for you. They may ask you to cut it up first.
 

Ryan Minchew

Well-Known Member
There wasn't a year or so ago. I looked into it for learning some machining myself. I did talk to a local machine shop, he gets 86 and hour for the surface ginder and said to expect at least 3 to 4 hours. That's hard for me to swallow for a 5 foot piece of steel 1.5" wide.I've never priced machine work so I don't know, but couldn't bring myself to pay that much. I could put that much to the mill I talkex about earlier.

Do you have a machine trades school close? Sometimes you can get the students to surface grind it for you. They may ask you to cut it up first.
 

Frank Niro

KNIFE MAKER
Ryan.
Harald Moeller, a friend knifemaker uses a fly cutter . For some reason he preffers it to his surface grinder.
 

Dan Seaver

KNIFE MAKER
There wasn't a year or so ago. I looked into it for learning some machining myself. I did talk to a local machine shop, he gets 86 and hour for the surface ginder and said to expect at least 3 to 4 hours. That's hard for me to swallow for a 5 foot piece of steel 1.5" wide.I've never priced machine work so I don't know, but couldn't bring myself to pay that much. I could put that much to the mill I talkex about earlier.
How much do you need taken off, do you need it an exact size or just flat in a .01+/- range, and would you be able to cut it into sections less than 18" long? I'm waiting on the last $55 to get my surface grinder running. If it runs as good as it looks I can do the work for you.
 

Ryan Minchew

Well-Known Member
Dan thanks for the offer, but I'm in no hurry and may have something worked out to where I don't have to ship it.

FWIW Dan and one other guy have offered to surface grind this for me off the forums, Great Folks Here
 

Bruce Bump

Forum Owner-Moderator
I use a surface grinder but any amount of heat build up allows the parts to raise up and take off too much material. I super glue the parts down for the best results but still need touch them on the flat disc. I just have an elcheapo 6" disc and use a foot switch to turn it on and off when my fingers get hot. I also use a height gauge to measure the parts and mark the high spots and grind just the marked high spots. Lastly I use the granite plate in the figure 8 motion.
 

Jim Adams Customs

Well-Known Member
There wasn't a year or so ago. I looked into it for learning some machining myself. I did talk to a local machine shop, he gets 86 and hour for the surface ginder and said to expect at least 3 to 4 hours. That's hard for me to swallow for a 5 foot piece of steel 1.5" wide.I've never priced machine work so I don't know, but couldn't bring myself to pay that much. I could put that much to the mill I talkex about earlier.
$250.00 to $350.00 grind a piece of steel flat? OK, this guy was brushing you off and if you didn't go away he was going to steal your money. The job actually takes less than 15 minutes should run you about $20.00.
 

Hankins

Well-Known Member
For that kind O money you can get precision ground from many of the suppliers.
Maybe USA Knife makers supply or Flatground.com for sure Admirals, Texas knifemakers supply or Sheffields
 

Ryan Minchew

Well-Known Member
$250.00 to $350.00 grind a piece of steel flat? OK, this guy was brushing you off and if you didn't go away he was going to steal your money. The job actually takes less than 15 minutes should run you about $20.00.
That's kind of what I figured. I'm doing some rearranging and what not and searching for a surface grinder. I'm starting to think my problem has two problems, the biggest of which is not parallel which maginifies everything else.

I've got a heavy duty Kuhlmann pantograph that will be in service next week, but I have the blacklip slip joint to finish up first. Jerry McClure gave me some ideas to try on it.

Thanks for the help
 
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