lapping compound

balibalistic

balibalistic

Joined
Jul 14, 2004
Messages
2,623
Hey guy's,

i use PB bushings on most of my balisong's. problem is, the O.D is always off spec just a couple thou. i generally ream before heatreat, then ream after to crawl up just a thou or two. i finally just ordered a 1/4" adjustable barrel lap to help save time and frustration. i'm just unsure which type of compound to get??

any pointers??
 
I bought a diamond paste from rio grande. It doesn't take much. I finally quit using the pb bushings for that reason. They seemed to add a couple of hours of work to a slip joint.
 
I've been wanting to get a lap because I plan on starting some folders soon. Where did you pick yours up?
 
Do you use many different size bushings? If you use maybe 2 or 3 sizes, I'd recommend making your own shim punch and die set.
 
Shawn...
I've been using the red "Super-Finish Diamond Lapping Paste, Oil Soluble, Grade #30" stuff from McMaster-Carr. I bought this when I first bought my 0.25" barrel lap, and have never used anything else. It has worked very well for me. The McMaster-Carr product number for the stuff I use is 4776A36 (5-gram tube/syringe). It doesn't take very much. Be careful not to over-lap your holes.

Erin
 
I don't know what PB bushings are, but why are they off spec?
Especially a couple thou, that's HUGE.

Clover compound is great.

Buy a small tin, as it will last you forever.
I recommend 400 grit.

I'd also have reamers in the sizes you need though, so you aren't lapping out .002"

Lots of folks sell them in .0005" increments.
 
Fellhoelter said:
I don't know what PB bushings are, but why are they off spec?
Especially a couple thou, that's HUGE.

I'd also have reamers in the sizes you need though, so you aren't lapping out .002"
Click to expand...

Hey Brian.
PB stands for Phosphorous Bronze. I don't use them, but I DO use the steel bushing/pivot assemblies from Knifekits. As you can see from the photo below, they mic in a bit over 0.25". I'm guessing that the reason they are made slightly oversized is so a maker can ream with a common size reamer, then have a little wiggle room to get a custom fit and cleaner finish with a barrel lap.
5044505598_250a30d7a2.jpg

Barrel laps are the best. :thumbup:
Erin
 
Ahh, that ain't off spec.
Bushings are generally made to be a press fit on the OD, with the theory that the shaft is spinning INSIDE of the bushing.

7 tenths is about right on a quarter inch bushing.

Now when I used to use bushings, I worked with the theory of the blade spinning around the od of the bushing too, so lapping is the way.
But, as a general rule, bushing OD's will be manufactured to a press fit.

I thought you guys were getting a variance of a couple of thousandths from part to part.
That ain't cool.
 
Fellhoelter said:
Ahh, that ain't off spec.
Bushings are generally made to be a press fit on the OD, with the theory that the shaft is spinning INSIDE of the bushing.

7 tenths is about right on a quarter inch bushing.

Now when I used to use bushings, I worked with the theory of the blade spinning around the od of the bushing too, so lapping is the way.
But, as a general rule, bushing OD's will be manufactured to a press fit.

I thought you guys were getting a variance of a couple of thousandths from part to part.
That ain't cool.
Click to expand...

Huh... that's funny (but the press-fit explanation does explain the oversize OD). I always have blade pivoting around the OD of the bushing, and use fine-tuning of the bushing thickness to allow me to establish "full-tight" on the pivot screws without pinching the blade.
Erin
 
Bit late on the response here guy's, been doing some house upgrades :thumbdn:

Erin pretty much covered it. i use the bushings from mcmaster. these bushings are not to the same tolorance as knifekits bushings..., those are a dream. the ones i use need the I.D reamed out and O.D turned down or pivot holes reamed larger. i ream pivots to .250 prior to heatreat, and .251 after heatreat. i find .252 is a tad excessive. this is where i'm hoping the laps will come into play.

johneymac, i picked up lap,shank and adjustable screw with 20 spare brass laps off ebay real cheap. i always keep an eye out for deals. they are accro. theres a bunch on there for sale but not the same seller.
 
Jonnymac... I missed you question too. Barrel laps can be purchased several different places online and are relatively cheap. I bought my 1/4" & 3/16" laps from McMaster-Carr for about $6 each. MSC sells them for about $8. Replacement barrel are usually $2-$3 each. Probably the most expensive component is the lapping compound, and it seems to last quite a while (I've probably only used 1/20th of my 5-gram tube so far). They are a very useful tool to have around.
Erin
 
Thanks brother, appreciate it! Was browsing Mcmaster-Carr and it was dizzying how many there are to look at. I'll check the bay.

Erin, thank you as well. They're on my short list.
 
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