Drill DoctorLarge Bit Chuck Sharpen 3/32" to 3/4" Bits for Models 500x, and XP. Replacement for 750X DA70100PF

I needed a new chuck because the original was badly worn, altering bit shape. It made sense to get the one that takes up to 3/4" bits. After comparing the two, the only difference is that the end of the standard chuck is constricted to limit bit size to 1/2". If my old chuck wasn't worn, I would have been fine w/ just cutting off the end. To verify, I did cut the end off my old one, and it functioned as well w/ 3/4" bits as the new one. If you do that, just be sure to back up the metal vanes by opening the chuck before you make the cut, and to extend the marks for masonry bits on the end of the chuck down along the sides, as you'll be cutting the old ones off.The Instructions that come w/ my DD500x were not as complete as they could be. Here are a few things I've learned that may be helpful.1. Lubricate the chuck. Applying a small amount of grease around the chuck shoulder where it rides on the cam (at the surface that faces toward the grinding wheel). This will allow the chuck to slide more smoothly as it is turned, making for both easier sharpening and reduced wear.I also apply grease to the threads that attach the two portions, making it a bit easier to tighten and release before and after sharpening, but that may be overkill.Had I lubed the surface that contacts the metal cam much earlier, my chuck would be in better working order now. They probably will still need replacement at some point of use, but should last a lot longer. Be aware that the cam shoulder will pick up grit over time, so clean and re-grease it periodically, and do the same w/ the interior, but less frequently.Be careful to align the vanes properly to reassemble, and don't force it. It goes together very easily.2. When aligning a bit in the chuck, I use the center slot as instructed. If the relief angle on the bit is too flat, I go one slot counterclockwise and regrind. In a few cases, I've had to go two or even three slots CCW to get the right relief angle. I do look at the clock angles shown in the instructions, but find it much easier to just look at the relief angle, especially on small bits.W/ a few bits, I've had the relief angle come out differently on one side than the other. In this case, I'll re-seat the bit once in the same slot and try again. If that doesn't correct it, I'll re-seat it one slot CCW, and re-grind.I like to check the bit after a few passes, and will often re-align a larger bit after the first several passes to make sure it's centered and to take a little more off the leading edge.I find it important to tighten the chuck very securely, otherwise the bit may to slip back in the chuck as you're grinding. If grinding reduces and/or stops after just a few passes, the bit has probably slipped back in the chuck. You can tell by putting it back in the alignment tool and checking for a gap. Rubber gloves give a very good grip and make a big difference here. I tighten the chuck while in the alignment tool enough that it won't slip, then remove it and tighten very securely w/ two gloved hands.3. When sharpening, I start w/ the white mark just left of the cam, then turn clockwise and come around, using light even pressure and making sure to keep the chuck centered, not tilted, and held lightly against the cam. I added a piece of white tape above one of the white marks so that I know which mark I'm starting on, so that I can finish w/ an equal number of passes on both sides.If I'm sharpening and hear that a lot more is coming off on one side of the bit compared to the other, I'll make a few extra passes on that side until the sound is about even, indicating better symmetry at the bit. The first portion of grinding will be the leading edge of the bit, so if you're trying to increase the relief angle, you'll want to hear "heavier" grinding during the latter portion of the pass. I also want to hear some grinding right at the start of the first few passes to assure I'm sharpening the leading edge. After those first few passes, the grinding will start later in the pass. Though the instructions say to continue until grinding stops, I find that three or four passes w/ small bits at light pressure is adequate, and about twice that w/ large bits, unless I'm changing relief angle or point angle. Be aware that, though there are two angles marked in the adjustment window, you can custom set the angle in between, and even a bit beyond each end.4. W/ smaller bits, it's sometimes harder to get a balanced split point. Note that the side you're grinding is at the bottom of the bit. I start w/ a few seconds on each side, then compare. I prefer not to take it all the way to a point, but leave it a little short of the point on each side. It takes very little time on small bits; better to start w/ just a few seconds at most w/ light pressure until you see what you're getting.If I can't get it to grind the split point as deeply on one side of the bit, I'll reach through the chuck hole w/ a small screwdriver or similar and press the bit down against the grinding wheel to assist.5. It's good to blow out the unit w/ a compressor from time to time, and don't forget that the screw that holds the grinding wheel on is left-hand thread. I lost the wrench they include, but a properly sized channel locks works just fine.

Exactly like the Bit Chuck that comes with 500x except it has a wider hole and you can sharpen bits up to 3/4 or 19.05 mm drill bits. If I had it to do over I would have gotten the 570 it already comes with this large bit chuck. The 570 is more but my the time you order this part the price will be close to the same. The question is does it sharpen bitts? I sharpened about 30 bits. I drilled before I would sharpen drill bit and then test after I sharpened. This thing works better than great it is Awesome! The makings of the holder is mostly plastic but the chuck that holds the drill bit are metal and gets the job done. Buy with confidence.

Good product wort very well on larger drills

When I purchased my Drill Doctor 500, it only came with an adapter chuck that would accommodate up to a 1/2" diameter drill bit for sharpening. Purchasing this Large Bit chuck will now allow me to sharpen drill bits from 3/32" up to 3/4" in diameter. It will be a welcome addition to my original Drill Doctor 500 unit without having to buy a whole new sharpener unit. I have yet to try it out, but it should operate as well as the original bit sharpening chuck that came with my original Drill Doctor 500.

tool was great but manufacture should put the bigger tool in first to fit 3/32 to 3/4" so you do not need to buy a second one

The chuck works great in my 550 Drill Doctor. Able to sharpen my Sliver Demming Drill bits up to 3/4 inch with no problems. Quick and simple sharpening with not stress or worries. Made it easy to drill through the 3/4 inch thick A36 steel bar as I needed.

This worked great with my existing Drill Dr XPK. It puts a nice sharp profile on the drill bits, just like my original 1/2" holder did. Anything bigger than 3/4" I sharpen by hand. I thought it was a little pricey for a many plastic piece, but I am very pleased with it overall.

Nothing to dislike