How to make a band cutting mandrel

[Brewz]

Hi Folks

My journey begins here and without a lathe, as most of we chainsaw enthusiasts are, I need to do the work by hand accurately and precisely.

Now i have had some help from a lather with a 54mm mandrel cut to fit snug inside an 066 cylinder.



I also have bought a 1/2" HHS cutting bit.

I am after any advice on how to set this up properly to get it cutting a nice squish band.
I can then sand the base to get my squish back. I dont care if I need to spend weeks doing it for my own saws as long as I get best results.

I have it im my head on how to fit it up but would like this to become an info thread for amyone ging forward on how to do it propery.

 

[Canadian farm boy]

 

[Milkman31]

Present!

 

[angelo c]

TreeMOnkey to the wesque....

 

[Chainsaw Jim]

That's what I use old scored up pistons for. I use a high grade super glue because it's brittle enough to scrape the sandpaper off cleanly for replacement.
I use 50 grit to start. I use plenty of glue around the edges so it helps hold the grit to the paper letting it cut nice and square. If the heavier grit falls off the edge of the paper it loses the ability to cut a sharp square edge and the bits can migrate up the bore, which scores the cylinder.
It's better to do it by hand so the sandpaper holds together and you can frequently clean the aluminum dust. A power drill will cause the sandpaper to booger up and fall apart.

 

[huskihl]

If you're going to use a mandrel with a hss cutter, you'll also need a sanding mandrel made of wood, plastic, old piston, etc. Don't use the hss mandrel to cut the entire squish band; use it as a ridge reamer to cut the very edge where the sandpaper misses. Tree monkey uses a wooden sanding mandrel to keep the squish the same depth all the way around, and then his hss mandrel to remove the ridge. If you try it only with the hss mandrel, your squish will vary by .005 - .010" depending on where you measure. There's no way to control the depth to within exacting tolerances by hand. The sanding mandrel keeps the band flat.

 

[grassguerilla]

 

[mdavlee]

I usually keep mine within .002-005" with the HSS. Some I don't even hit with a sanding mandrel anymore. I check 4 corners before I start grinding for porting after cutting the squish. I do the base first.

 

[idiotwithasaw]

Very interested in this.

 

[rattler]

Here is one for a 52mm

 

[angelo c]

@drf255

 

[ABarrick]

Have any of you seasoned saw molesters tried delrin for your mandrels? Curious if it will hold up or me sturdy enough to not deform under cutting pressure. I like the idea of it for bore protection as it would be pretty hard to scratch anything with it but don't want to waste a ton of money on making some out of it just to toss em out.

 

[Deets066]

I cut two flat spots opposing each other. Makes it solid in the vice.

 

[Deets066]

I used a 90 degree head on my mill to cut the slots for the HSS

 

[drf256]

I usually keep mine within .002-005" with the HSS. Some I don't even hit with a sanding mandrel anymore. I check 4 corners before I start grinding for porting after cutting the squish. I do the base first.

I've made a Delrin sleeve/collar to fit around the bottom of mine as a stop. It's a bit tedious to set up, but it prevents cutting too deep or making notches. I find that setup correctly, I need almost no sanding with this method.

I just use a feeler gauge between the bottom of the jug and the collar for the max amount I want to take off, then I secure it with a hose clamp.

 

[Tor R]

What do your guys use as materiale for your mandrels?
If 45mm bore, what tolerance do your guys prefer the mandrels to have?

 

[drf256]

What do your guys use as materiale for your mandrels?
If 45mm bore, what tolerance do your guys prefer the mandrels to have?

I personally go .08mm less. So for your 45mm mandrel, I'd go 44.92 mm

 

[Tor R]

I personally go .08mm less. So for your 45mm mandrel, I'd go 44.92 mm

thanks Al,
Do you use iron or aluminium mandrels?

 

[drf256]

I used aluminum. Your cutter will be flush with the bore.

 

[drf256]

I used a 3* cutting angle Tor