Making a depth gauge/raker grinding fixture

This is the making of the Fixture to grind Depth Gauge or Rakers on chainsaw chain to equal depths and easier. I've done it by hand for years bur wanted something that would make this job easier and better at the same time. I have a surface grinder here at home and will use that as the way to grind. the fixture will just hold the chain and be adjustable for any chain out there.



Went to the metal piles and grabbed some stock. I'll use stainless on the guides and pins and mild steel for the base. That way it'll be magnetic when put on the surface grinder chuck and will hold.



Here's my surface grinder. I put a digital readout on it so I can repeat easily and redress, going back to the exact spot. You can do it without, which I have, but this makes it a lot easier



To hold the chain in place I'm planning on a snap clamp. They are adjustable and hold really well.



Here's a VERY rough sketch of what's in my head so you have an idea of where I'm trying to go with this



I cut 4 pieces for the chain holder and want to round the ends like a saw bar so the chain doesn't catch. Cut them the same and marked the ends. I threw in on the surface grinder to cut 45 degrees of the excess stock off.



You can get real close and make straight cuts with these.



This makes short work for rounding if you don't have a mill like me.



Marked a center hole and I'll do this on both ends. This will hold the together, evenly while I work them up.



Center drilled and drilled all the holes.

 

I see where you're headed - and it looks great

 

Now I put a round spacer between them and another spacer on the other end, bolting it together. Ink a line and will rough it in with an angle grinder, not touching the ink.



Less than a minute to this.



I then mounted a belt sander in a vise and bl;ended to the ink. Just barely touching it. You can see it makes a nice, even, rounded edge.



Some 150 grit sandpaper on a soft back pad and you have this.



I need something to align the 2 halves when the chain is in it so a couple of dowels are in order. I'll put them fairly close to the ends on center so i marked and drilled them a little undersize of the final .375 hole. I'm reaming it here to the final size.



Cutting the dowels here in one swipo to 1.000 long. Touch of on the end of the rod and zero out. Move in 1.000 + .050 for the wheel and they are basically all the same.



The readout will spoil you in a hurry!



Quick deburr and they're done.



With both sides together I slide the dowel in to flush. If you are a little small and need a way to hold snug. Dimple it with a center punch on the end to be welded. An old trick that still works.

 

Wish I had these fab skills.

 

I'm definitely paying attention.

 

You can pick these up pretty cheap but you have to know what to look for as far as wear goes. Spindles run around $1000.00 USED from dealers so don't get one without a good spindle. I got this one for less than $200.00 off Ebay and it was local, from a dealer. He was not happy they didn't put a reserve on it. I was!

Never tried blades yet. Most times and angle grinder is quicker. Long straights like to warp on a surface grinder if you are not flooding it with coolant. It's a constant heat path that does it. If I had a choice, I'd say milling with carbide inserts would be better.

 

TIG weld it in.



No filler rod needed.



Both sides are doweled here. On shorter chains I'll just need one side. On 18 inch and longer I wanted to have something that would hold the chain so it doesn't tangle and get caught on stuff. Just trying to cover a lot of different set ups while I'm doing it.



For the back half I wanted an adjustment for width. Might not be needed but it's nice to have options. I first drilled and tapped a 1/4 -20 hole through both pieces. while they were together.



Then drilled to .250 and counterbored with a .500 drill on the inside of the bar. This is so a nut can be flush when completely closed.



I then reamed it to a flat bottom.



Nut sits flush now and I can locktight to a wingnutted socket head cap screw. This way this half will spin and with threads on the other side, it will move in and out with the dowels keeping it inline.



Here it is all together. Works really well.



Now I need a couple pieces that will allow adjustment of the 2 halves. Decided to use a .750 x 2.000 bar stock and I'm cutting them here to 1.500 long.

 

Using this system I can cut right to size.



The 2 blocks done so now I'll drill and ream them to .440.



Clamped them both together and drilling all the way through. Spacer block supports the bottom so it doesn't move and drill has a gap. Having a mill with a mounted vise would be nice....some day.



Reaming to size here and they should be real smooth when adjusting.



Works fine and now I'll drill and tap for a wing nut socket head cap screw to hold the adjustment in place.



Doing some layout here to see the best position. I'm shooting for 36 inches at full extend. I do have a 4 ft bar and chain on one saw but I'll either make up longer rods or let it hang. I'll cross that bridge when I get there.



Need a thick piece for the upright so off to the scrap pile. Improvising on the cut. I do these by putting a large, true plate on the magnetic chuck, then clamp the cut material to that to get a straight edge. I can cut clear through this way with one set up.



With this edge I can just put it on the chuck and they will be parallel. I cut half way through, then flip it over and finish.



Here you can see how it works. for the other 2 sides I'll use a straight edge square on the cut and it will be a true 90 degree cut.

 

Living room? There's always room for good tools.

 

Back to the holders. Clamped it all up on the table and double check to ensure easy movement. I then Tack it and recheck.



TIG weld it to finish so they are set in place now.



Really like how this is turning out.



Decided I wanted the upright plate on the same side as the rods. I want the opposite side clear as the clamp needs to be over there. Ended up drilling all the way through the plate for the rods to pass through here when collapsed down, I over sized these top .500



More Mock up. Marking where the clamp will go. I'll drill and tap one hole first and check.



With that done I now have another hand for the final location of the other 3 holes.



Scribed the circles from the clamps mounting holes and center punch them. I'll drill and tap the rest now.



I'll cut the base now. I need it about 7.500 inches long as I want it to overhang the chuck some. This will allow down clearance when the handle releases. Basically a knuckle saver. Using a speed square here to get a nice 90 degree cut.



Once cut, I skimmed the bottom of the plate. This is more of a demonstration to prove how much steel moves around when heated /welded on. It took less than .002 of stock removal to get it like this.

 

Tacked the upright to the base and before final welding I want to add angle supports. This will keep it at 90 better as heat will warp and pull stuff around. Got a scrap and cutting to size here.



To cut consistant angles on the chuck, this is how I do it. I simply measure the corners till they are the same.



Works like a charm.



After tacking the angles in, I started final welding it all. Using the MIG welder for this as it fills the gaps in easier for me.



After welding and letting it completely cool down, you can see where now it is high in the middle. I've zeroed out on the diamond so we'll see how much it takes. You have to do this slow and with coolant taking .0001's at a time on final passes. If it's warm to the touch, you're taking off too much.



After a lengthy grinding session, it is flat again. This is .500 thick steel.



Grand total was .0074 stock removal. Welding will move things around so always be aware of that and leave extra stock if neede



The holes I drilled earlier to align the bars for rounding serve a double purpose. I'm recessing them and installing springs. This will make opening/closing/adjusting very simple.



This will keep equal pressure on the ends so there is no binding.

 

I then TIG welded the Mild steel base to the stainless bar holder.



Wanted to have a little more clearance where the chain will pass by the clamp so I dressed a radius in the wheel. I can set the diamond to any size I like, either concave or convex. This will come into play when I dress it to grind the rakers.



Need an index stop for the backside of the chain so I got a piece of .550 square brass stock. Using brass so it won't nick the chain when grinding them all. Drilled a .250 hole for a pivot first.



Ground some angles and reliefs to make it both functional and look better.



For the stop I decided to have a pivot arm. This way I can have adjustment on the stop. With the surface grinder May not be needed but once again, nice to have options. Cutting a .500 x .500 square length from a plate here.



Drilling the pivot holes. Center and arm end are .250 the other end is reamed to .375.



For the swivel adjuster I drilled and tapped 10-32 threads both ways. Really not necessary on the ends as it is trapped but I like doing that as you can have a reserve for grease to lube the thread all. I did it on a tang to hold it easier, then cut off.



Here it is assembled and is real smooth.



I then drilled and tapped for the center swing.

 

Back to the scrap drawer and made a bushing to center the chain stop. I'm leaving the brass long till I'm done. haven't decided on what to do there yet. Whether it needs a handle or if it will just hop to the next link.



Milled a slot for the adjustment stop. Need some up and down ability as the arc of the arm moves that way.



Marked the holes on the fixture and drilled and tapped those. The bolts needed I didn't have on hand so I threaded some longer ones down and will cut to length. I made up some bushings as well to set it back farther. Gives me more adjustment and less crowded where the knob will be.



All on and everything works well. Now for the knob.



Using a press on knob for this. These are designed to press onto a socket head cap screw. I cut one off short and now will gun drill and tap it for 10-32 thread.



Drilling the shcs through the head using a bushing to hold it in the lathe.



Once it was threaded I pressed on the cap/knob in the arbor press. A normal bench vise work well too.



These make nice knobs and you can use whatever size thread you want this way.



Put it together and works!

 

Nuts lock it down and allow it to slide up and down without binding. Tight enough that there is very little in and out play so the stop will repeat the position of the chain.



To finalize the clamp hold down I had to make a threaded insert. I'm using a table or chair swivel from the home center and the studs are too short to reach through. I'll just thread the swivel in and adjust the length with washers as the clamp wears.



A few tacks are all that is needed.



I also decided to put a 10-32 set screw as close to the edge as possible where the chain is being held. This will give it a little extra binding in that area and will be adjustable/replaceable as well.



I surface ground the opposite side of the set screw for even pressure and so it doesn't dig into anything.



The indexing arm needed a little more clearance for the chains next cutter back so I'm relieving it here.



Now there is plenty of room.



Ready to try it out! Stihl used a .210 radius so that is what I'll go with. I'll do a portion radius and dress down .060 and in .250. This will give me a .040 flat to play with. I want to keep the flat around .010. Don't know if that is correct but that's what I'll try.



Starting with an older chain that the rakers have been ground on all ready. Chain was sharpened and I tried it on the saw. Did fine but seemed to have more vibration and bounce than a new one. here is the raker before.

 

Here it is after. Quite a difference. It was VERY telling on how much it varied as I went around the chain and did them all. Some didn't touch so when I put it back on I don't know how much of a change I'll see. This chain has been sharpened a lot. I need to get a first time sharpened chain that had hard damage or something to where a lot of the tooth was take down at once.



This is the set up for an 18" chain. Went really smoothly



Decided I wanted a little bigger handle for the snap clamp. the clamps do wear out so I'll make the handle so I can reuse it. Drilling it here to slip over the rectangular shaped end.



Slipped it over that and marked where my fingers normally would be. I marked those and will recess some there for a grooved type grip.



Drilled and tapped for a couple set screws to hold it on and rounded /angled the ends as well.



Handle makes it have a nicer feel too.



For short loops I thought I'd just let them hang but it is so much nicer to have them taught ads it indexes easier. Going to make up a roller assembly for those. Started by duplicating another slide block from the same bar as before.



Found an old belt pulley with a .500 center hole. I drilled and tapped for a slide bar hold, then drilled and tapped for a 1/2 course thread. This way I can thread it in and use a single nut to lock it on, allowing the pulley to spin freely.



Works like a charm.

 

You may be my new best friend.

 

Fixed that for ya(?)