I really like the feel of the old school Snap On Hard Handle ratcheting screwdrivers, p/n SSDMR4B(color code), but I prefer the ability to interchange shanks like the new ones can (p/n SGDMRC4A(color code)).
I searched this forum and found this thread:
Taking apart a Snap On Screwdriver
But I learned some things that may be helpful to those wishing to convert their fixed shank drivers to interchangeable shank. Chiefly, I believe I determined the true purpose of the washer in the ratcheting selector cap, discussed at length in the thread above.
1) Begin by removing the end cap. It is held in place by a snap ring, which can be accessed thru a recess in the end cap. There is no need to mark anything. The recess is always directly opposite the logo. When the end cap/selector is in the middle position (locked in both directions), it will be perfectly centered on the flat opposite the Snap On logo.
View media item 41323
In this picture, I haven't yet set the end cap selector to the mid position. You can move it back and forth to help get at the snap ring without scoring the plastic. You can't just stick a pair of pliers in there and and pinch the snap ring.
2) You will need fine needle nose pliers to squeeze the snap ring ends together.
View media item 41320
3) Slide the end cap off. It is likely some of the balls/parts from the ratchet mechanism will stick to the end cap. Carefully put these back where they go on the handle. It should look like this:
View media item 41324
4) Remove the spring washer from the shank using a pair of duck bill pliers or similar. Slide the shank out of the end cap. The end cap should look like this:
View media item 41316
5) This is the part I think others haven't misunderstood. The recess or counterbore in the center of the end cap is there for the spring washer only. If you reassemble now, your screwdriver will function fine and the new shanks with the spring loaded balls will be retained in the handle just fine.
The problem people have encountered is, with the washer gone and nothing in the counterbore, the ratchet gear is free to move axially. Here you can see it pulled out proud of the handle. It is designed to sit flush with the top surface.
View media item 41310
Without the washer, the screwdriver shaft will move in and out of the handle, pulling the ratcheting gear with it.
6) The solution is to simply fill in the recess with something; virtually anything will work. I have tried two different low cost solutions- both washers- black rubber neoprene is what Snap On used to make the interchangeable shanks. These washers actually don't touch the shank and do nothing to hold the shank securely. They only prevent the ratchet gear from moving axially. It is important to note that this is a wear surface and should be lubricated. I recommend Super Lube.
View media item 41319
Here, a nylon washer has been fitted This is a standard M8 washer. It has a 16mm OD and clearance for a 8mm shaft. The Snap On shanks are all roughly 8mm.
A hard M8 washer will need to be filed down slightly to fit properly. The counter bore has a 15.5mm diameter. It took me a few minutes with a flat file to get this to fit properly. A standard M8 rubber washer fits perfectly. The depth of the counter bore is about 1.7mm. Washers are available in veering thickness. These metric washers are typically available in 1mm, 1.5 or 1.6 or so, and 2.0mm. The 1.5-1.6mm washers work best.
The fit between the cap and the shanks is fairly tight. Not much play here and no need to reduce the clearance with a washer.
View media item 41309
7) Once the washer is fitted, lube lightly with Super Lube or your favorite lubricant. I squeezed the snap ring on the handle side and simply slipped the end cap with the new washer fitted over it. Once in place you can release the snap ring and viola! Now your HH screwdrivers can accept the interchangeable shanks.
Last: I fitted one nylon and one rubber washer. If I understand the ratchet correctly, the ratchet gear moves relative to this washer only when operating the send cap/ratchet selector. My assumption was that the harder nylon washer would feel better, smoother, and permit a more satisfying click. I was wrong. I detected virtually no difference between the rubber and nylon washers. Use the rubber M8 X 16 X 1.5mm washer (like Snap On did).
Only other caution is about applying the wrong kid of lube or too much of it. One of the things that makes these screwdrivers great is their super low back drag when ratcheting. I have three SO ratchet screwdrivers and none of them seemed to have much of any oil or lubricant in them. Super lube probably increased the back drag slightly. I may have done better with a light coating of 3 in 1 oil.
I searched this forum and found this thread:
Taking apart a Snap On Screwdriver
But I learned some things that may be helpful to those wishing to convert their fixed shank drivers to interchangeable shank. Chiefly, I believe I determined the true purpose of the washer in the ratcheting selector cap, discussed at length in the thread above.
1) Begin by removing the end cap. It is held in place by a snap ring, which can be accessed thru a recess in the end cap. There is no need to mark anything. The recess is always directly opposite the logo. When the end cap/selector is in the middle position (locked in both directions), it will be perfectly centered on the flat opposite the Snap On logo.
View media item 41323
In this picture, I haven't yet set the end cap selector to the mid position. You can move it back and forth to help get at the snap ring without scoring the plastic. You can't just stick a pair of pliers in there and and pinch the snap ring.
2) You will need fine needle nose pliers to squeeze the snap ring ends together.
View media item 41320
3) Slide the end cap off. It is likely some of the balls/parts from the ratchet mechanism will stick to the end cap. Carefully put these back where they go on the handle. It should look like this:
View media item 41324
4) Remove the spring washer from the shank using a pair of duck bill pliers or similar. Slide the shank out of the end cap. The end cap should look like this:
View media item 41316
5) This is the part I think others haven't misunderstood. The recess or counterbore in the center of the end cap is there for the spring washer only. If you reassemble now, your screwdriver will function fine and the new shanks with the spring loaded balls will be retained in the handle just fine.
The problem people have encountered is, with the washer gone and nothing in the counterbore, the ratchet gear is free to move axially. Here you can see it pulled out proud of the handle. It is designed to sit flush with the top surface.
View media item 41310
Without the washer, the screwdriver shaft will move in and out of the handle, pulling the ratcheting gear with it.
6) The solution is to simply fill in the recess with something; virtually anything will work. I have tried two different low cost solutions- both washers- black rubber neoprene is what Snap On used to make the interchangeable shanks. These washers actually don't touch the shank and do nothing to hold the shank securely. They only prevent the ratchet gear from moving axially. It is important to note that this is a wear surface and should be lubricated. I recommend Super Lube.
View media item 41319
Here, a nylon washer has been fitted This is a standard M8 washer. It has a 16mm OD and clearance for a 8mm shaft. The Snap On shanks are all roughly 8mm.
A hard M8 washer will need to be filed down slightly to fit properly. The counter bore has a 15.5mm diameter. It took me a few minutes with a flat file to get this to fit properly. A standard M8 rubber washer fits perfectly. The depth of the counter bore is about 1.7mm. Washers are available in veering thickness. These metric washers are typically available in 1mm, 1.5 or 1.6 or so, and 2.0mm. The 1.5-1.6mm washers work best.
The fit between the cap and the shanks is fairly tight. Not much play here and no need to reduce the clearance with a washer.
View media item 41309
7) Once the washer is fitted, lube lightly with Super Lube or your favorite lubricant. I squeezed the snap ring on the handle side and simply slipped the end cap with the new washer fitted over it. Once in place you can release the snap ring and viola! Now your HH screwdrivers can accept the interchangeable shanks.
Last: I fitted one nylon and one rubber washer. If I understand the ratchet correctly, the ratchet gear moves relative to this washer only when operating the send cap/ratchet selector. My assumption was that the harder nylon washer would feel better, smoother, and permit a more satisfying click. I was wrong. I detected virtually no difference between the rubber and nylon washers. Use the rubber M8 X 16 X 1.5mm washer (like Snap On did).
Only other caution is about applying the wrong kid of lube or too much of it. One of the things that makes these screwdrivers great is their super low back drag when ratcheting. I have three SO ratchet screwdrivers and none of them seemed to have much of any oil or lubricant in them. Super lube probably increased the back drag slightly. I may have done better with a light coating of 3 in 1 oil.
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) but no success. I'd like to find a part number that I could order. I'm going to try this on one of my Williams ratcheting screwdrivers. If it works well I may convert all my Snap-on screwdrivers too.
