- Joined
- Jun 4, 2010
- Messages
- 6,642
Write up of the homemade guided system I made. Is simple, but not easy. Has been around for years now and have posted up some pics and a couple of videos of older versions, but recently solved the last major obstacles to improve practical use.
The initial drive to build it was a way to get a guided system that would work with any benchstone setup - this was non-negotiable. Evolved to something that could seamlessly go from belt grinder to benchstone.
The most expensive part of this is the aftermarket Tormek benchgrinder adapter hardware. No jury rigged approach yielded anything as stable or finely adjustable as this solution. Mounted to an automotive scissor jack it can accommodate any of my benchgrinders, waterstone bridges, benchstone holders.
Consists of two parts, a clamp body with contact guide arm that holds the knife, and height adjustable guide rod. The clamp body is nothing more than a draw nut attached to a belt that pulls the knife handle into a padded jaw. The draw nut rides in grooves to prevent the entire belt from twisting inside the clamp body as its tightened. Guide rod can be positioned out over a stone/belt or butted up to one end.
It is capable of applying a lot of force, but manages to get a very firm grip without having to squeeze too hard - just enough to keep the handle from rolling. Thin and skeletonized handles require the highest pressure to prevent rolling. Earlier versions had an articulated jaw that solved this problem but became a weak point prone to breakage.
Centering is done by eye, most knives that have symmetrical handles will drop right into place, some need to be carefully positioned - this can be the biggest time suck of the entire process sometimes. If the blade is not centered in the handle, the guide rod height will have to be tweaked per side. Due to the Tormek micro adjust nut this is actually not much of an issue. Also makes it possible to quickly correct (or match) off center or asymmetrical grinds.
Once clamped, the contact guide arm is aligned parallel with the bulk of the blade. You would think this will cause issues tracking around the belly and tip, esp on different belly curvatures. Have done 100s of knives on it and only one would not track - a serrated Mora rope knife. Is also possible by angling the contact guide arm to change the angle from heel to tip. This comes in handy for overbuilt tactical knives where it is impossible to lower the angle at the plunge line but can become more acute as it approaches the tip to improve performance. Invaluable for grinding helical edges or maintaining the twist on hair shears.
It is possible to set the grind path/tooth angle across the bevel to any angle - contact angle does not change unless the guide arm is not parallel to bulk of the edge. In that case the blade contact area should be perpendicular to the long edge of the stone, or if using an angled rake path it needs to be consistent in its angle of movement across the stone at the contact point.
It is adjustable for angle from 90 to 0 or lower if you have clearance. Once the proper angle is known, it can be "recorded" with an adjustable carpenter's square. It can now be used on ANY abrasive surface - other thickness stones, horizontal belt grinder etc.Still, use of diamond plates that share a common thickness is ideal if using 100% manual.
There is a second guide rod that can be mounted underneath the first (not pictured) allowing the edge to be 'floated' between two points for crafting a convex edge with precise stop and start angles. Curvature shape between the points involves some voodoo/skill, but still pretty precise.
The same clamp body can be used with a perpendicular guide rod and an oversized widget that looks like the Tormek chisel holder. This allows the same flexibility in angle control with a short bladed chisel (clamp the handle) or odd tool sharpening, the flat guide arm clamps into the holder for control on two axis. Have a scaled down clamp body for doing shears that also works well for dental tools etc. Set-up time can become prohibitive on some items, but if angle precision is more important than $/time it can do whatever. Have also reground the hollow underside of some hair shears to restore proper contact. This requires a wet wheel of same or smaller approximate diameter as was used at the factory.
Due to the guide rod being adjustable for height and slope, it is possible to grind fairly precise distal taper, plunge lines etc. The process is not the fastest, but it IS accurate.
There are clamp body adapter and guide arm extender to 24" making it possible to do machetes with the same accuracy, either by hand or machine.
Biggest drawbacks are the weight/mass of the clamp body when using it on benchstones as you have to push/pull the entire thing. This is offset somewhat by fact that most of the weight is resting on the guide rod. Is still reasonably fast though, since one can make use of the entire stone length per pass if desired. The ideal means of use are to regrind the edge by machine and refine on several stones or simply microbevel by hand.
As with any guided system, it has weak points - the clamp belts have been known to blow out, if the knife is not clamped securely enough the angle will drift off as you work. It is somewhat cumbersome to change sides quickly. But, it does not scratch the blade or handle with the clamp - it is 100% non marking. It works with existing benchstones etc. For 80% of all knives it clamps and centers in a minute or less.
I don't use it very often - only on very high end (esp DLC coated) knives or if a specific angle has been spec'd, or if I have a pile of cheap knives where precise angle is not important - I'll set up the first knife on belt grinder to 14°/side, set a second one at 16° on a manual finishing stone - grind and micro, rinse and repeat - can pound through a lot of knives very quickly and edge quality is almost as good as my freehand.
Ironically in the few years it has taken me to perfect this widget, my freehand has continued to improve in speed and accuracy, so I don't use this very often at all anymore, even for chisels. But, I do keep it in good working order. I will not do any powered grinding/sharpening on a belt without this guide.
The initial drive to build it was a way to get a guided system that would work with any benchstone setup - this was non-negotiable. Evolved to something that could seamlessly go from belt grinder to benchstone.
The most expensive part of this is the aftermarket Tormek benchgrinder adapter hardware. No jury rigged approach yielded anything as stable or finely adjustable as this solution. Mounted to an automotive scissor jack it can accommodate any of my benchgrinders, waterstone bridges, benchstone holders.
Consists of two parts, a clamp body with contact guide arm that holds the knife, and height adjustable guide rod. The clamp body is nothing more than a draw nut attached to a belt that pulls the knife handle into a padded jaw. The draw nut rides in grooves to prevent the entire belt from twisting inside the clamp body as its tightened. Guide rod can be positioned out over a stone/belt or butted up to one end.
It is capable of applying a lot of force, but manages to get a very firm grip without having to squeeze too hard - just enough to keep the handle from rolling. Thin and skeletonized handles require the highest pressure to prevent rolling. Earlier versions had an articulated jaw that solved this problem but became a weak point prone to breakage.
Centering is done by eye, most knives that have symmetrical handles will drop right into place, some need to be carefully positioned - this can be the biggest time suck of the entire process sometimes. If the blade is not centered in the handle, the guide rod height will have to be tweaked per side. Due to the Tormek micro adjust nut this is actually not much of an issue. Also makes it possible to quickly correct (or match) off center or asymmetrical grinds.
Once clamped, the contact guide arm is aligned parallel with the bulk of the blade. You would think this will cause issues tracking around the belly and tip, esp on different belly curvatures. Have done 100s of knives on it and only one would not track - a serrated Mora rope knife. Is also possible by angling the contact guide arm to change the angle from heel to tip. This comes in handy for overbuilt tactical knives where it is impossible to lower the angle at the plunge line but can become more acute as it approaches the tip to improve performance. Invaluable for grinding helical edges or maintaining the twist on hair shears.
It is possible to set the grind path/tooth angle across the bevel to any angle - contact angle does not change unless the guide arm is not parallel to bulk of the edge. In that case the blade contact area should be perpendicular to the long edge of the stone, or if using an angled rake path it needs to be consistent in its angle of movement across the stone at the contact point.
It is adjustable for angle from 90 to 0 or lower if you have clearance. Once the proper angle is known, it can be "recorded" with an adjustable carpenter's square. It can now be used on ANY abrasive surface - other thickness stones, horizontal belt grinder etc.Still, use of diamond plates that share a common thickness is ideal if using 100% manual.
There is a second guide rod that can be mounted underneath the first (not pictured) allowing the edge to be 'floated' between two points for crafting a convex edge with precise stop and start angles. Curvature shape between the points involves some voodoo/skill, but still pretty precise.
The same clamp body can be used with a perpendicular guide rod and an oversized widget that looks like the Tormek chisel holder. This allows the same flexibility in angle control with a short bladed chisel (clamp the handle) or odd tool sharpening, the flat guide arm clamps into the holder for control on two axis. Have a scaled down clamp body for doing shears that also works well for dental tools etc. Set-up time can become prohibitive on some items, but if angle precision is more important than $/time it can do whatever. Have also reground the hollow underside of some hair shears to restore proper contact. This requires a wet wheel of same or smaller approximate diameter as was used at the factory.
Due to the guide rod being adjustable for height and slope, it is possible to grind fairly precise distal taper, plunge lines etc. The process is not the fastest, but it IS accurate.
There are clamp body adapter and guide arm extender to 24" making it possible to do machetes with the same accuracy, either by hand or machine.
Biggest drawbacks are the weight/mass of the clamp body when using it on benchstones as you have to push/pull the entire thing. This is offset somewhat by fact that most of the weight is resting on the guide rod. Is still reasonably fast though, since one can make use of the entire stone length per pass if desired. The ideal means of use are to regrind the edge by machine and refine on several stones or simply microbevel by hand.
As with any guided system, it has weak points - the clamp belts have been known to blow out, if the knife is not clamped securely enough the angle will drift off as you work. It is somewhat cumbersome to change sides quickly. But, it does not scratch the blade or handle with the clamp - it is 100% non marking. It works with existing benchstones etc. For 80% of all knives it clamps and centers in a minute or less.
I don't use it very often - only on very high end (esp DLC coated) knives or if a specific angle has been spec'd, or if I have a pile of cheap knives where precise angle is not important - I'll set up the first knife on belt grinder to 14°/side, set a second one at 16° on a manual finishing stone - grind and micro, rinse and repeat - can pound through a lot of knives very quickly and edge quality is almost as good as my freehand.
Ironically in the few years it has taken me to perfect this widget, my freehand has continued to improve in speed and accuracy, so I don't use this very often at all anymore, even for chisels. But, I do keep it in good working order. I will not do any powered grinding/sharpening on a belt without this guide.
. Borg be dammed.