Building a Chain Sharpening Mandrel
I built this chain sharpening mandrel for Art Martin who was a long time poster to this form. He taught me a few things about hand sharpening chainsaw chains for cutting firewood, milling and also his race saw chains. He was quite the guy to know. So I built this chain sharpening mandrel for Art. You will see pictures and descriptions of the first mandrel I built for myself and I will try to explain how I fabricated the mandrel.
List of Materials
2) 6” long x 5/8” min to 1” wide x 1/8” or 4mm thick planer or joiner blades
4) 1” x 1-1/2” x 1/8” mild steel, flat stock
1) 1-1/2”W x 9” long x 1/8” thick, mild steel, flat stock
1) 2” x 2” x 3/8” x 5” long angle iron
1) 5/8”- 18NF X 3” long bolt
1) 5/8” -18NF nut
1) 1-1/2” long x 2” wide x 1/8” thick flat stock (used to shim the locking bolt to correct height)
2) ¼-28 NF x 1” long bolts
2) ¼ -28 NF NI-lock nuts
1) ¼ “diameter hardened round stock x 5” long (I made mine from an old tapping handle)
After cutting a 5” piece of 3/8” thick x 2”x 2” angle iron I welded the 9” long x 1-1/2” flat stock to the back of angle iron. I measured down 3/8” from the top-back of the angle iron. Keep it square to your measurements for welding.
This is what it should look like from the front.
The next step is to tig-weld the 1-1/2” x 1” x 1/8” mild steel flat stock to the planer blades.
On a flat welding surface I tig-welded the 1” wide surface flush with the bottom side of the blade. It is important to keep the blades and add on pieces flat to your flat welding surface and weld both sides. If you don’t have a tig-welder to do this part, take it to a shop that can do this process for you. Be sure to dull the cutting edge of the blade as it will be facing down.
Once the blades and add on pieces have been welded and any welding beads ground smooth, flush the two blades together and clamp them together. Tack the two blades together (small tac’s) on the add-on welded pieces. This will now allow you to drill the two ¼” holes needed together at the same time and to hold the blades in perfect alignment when installed on the base.
When you prepare to drill the holes in the add-on welded pieces I marked and drilled mine ½” from the top and ½” from the side. This gives the chain drive teeth clearance up to .404 chains to pass over the bolts without hitting the bolt shoulders.
With the holes now drilled in the blade add-on pieces clamp the tac welded blades to the front side of the backing plate welded to the angle iron. Clamp the blades 1/8” above the backing plate and use the holes as a guide and drill the ¼” holes in the backing plate. Remember, camphor the holes after drilling.
Leaving the bolts to hold the two blades together, use a bench grinder, belt sander or a had grinder and radius the corners of the add-on pieces and remove the tac welds. A quarter is a good radius size.
With the 1” long shouldered ¼”-28 bolts/NI-lock nuts, put a 1/16” thick ¼” flat washer between the blades and bolt the blades to the backing plate you drilled the holes in. This shim washer allows the blades to spring back when releasing the jam bolt pressure.
Welding and drilling the blades for perfect alignment is probably the most important process in building this mandrel.
Adding the Jam Bolt
In this picture you can see that I drilled ¼” holes through the head of the 5/8”-18 bolt. You only need one hole, but it looks trick with holes on all flat surfaces of the bolt head. I used a couple pieces of rubber tubing on each end of the T-handle to keep it from sliding out.
Adding the nut that holds the drive bolt at the proper height will depend on the width of planer or jointer blade you use. I spaced the nut with the bolt installed so that as the bolt protrudes from the nut the top of the bolt is approximately ¼” from the top of the blade. So the spacer thickness may vary depending on your blade width.
Once you have decided on the correct space thickness center the spacer and tac weld it to the base. Tac weld the 5/8-18NF nut to the spacer with the bolt installed so that the nut is ¾” from the surface of the blade. It is important to keep the bolt square to the blade. When you are sure the bolt is square to the blade, finish weld the spacer and nut.
With a DA hand grinder or belt sander, smooth the end of the bolt, you want a smooth flat surface when you tighten the bolt to the blade surface.
With a bit of paint, your color of choice, and a few drops of oil on the jam bolt, you’ll be ready for chain sharpening. Just a note: I never painted mine; I was in too much of a hurry to use mine and didn’t want to wait for paint to dry.
Hope this will inspire someone to build their own chain sharpening mandrel.
820wards
jerry-
