Has anybody here re-ground their valve seats by hand, with a grinding stone and power drill?
I've seen my regular machinist do it with a proper setup and it took about 10 minutes. It seems to me you could do it with a power drill and the right guide and stones. Dave_C had a great photo in the forum of him apparently doing it by hand with a tool that looked like it came from harbor Freight, and I'd be really interested in knowing how that came out, what he used and where he got it.
What size stone(s) would you need, and where do you get it? 30, 60 and 45? Would just the 30 work for the valve neck?
Valve Seat Grinding and Stones
Re: Valve Seat Grinding and StonesThe surface where the valve seals is the 45 degrees one.
The other two are used to narrow that land whne you have the valve seating nicely. Many years ago I did the seats on a Honda ST70 using a stone that I shaped myself. That stone had a 1/4 inch shank and it was easy to turn it down to 5.5mm for the Honda. Nowadays I use a (expensive) Neway cutter set but I bought a cheap set from India to do a CB400F head. If you want to use grind stones, the Black & Decker system is probably what you need. https://www.ebay.co.uk/itm/TOP-QUALITY- ... SwyQtVt6H7 https://www.ebay.co.uk/itm/VALVE-SEAT-G ... Swu4BVs1-5 https://www.ebay.co.uk/itm/TOP-QUALITY- ... Swj9lZqlFr G G
'60 C77 '60 C72 '62 C72 Dream '63 CL72
'61 CB72 '64 CB77 '65 CB160 '66 Matchless 350 '67 CL77 '67 S90 '77 CB400F
The Neway cutters are by hand, aren't they? As are the India cutters? How did the India cutters work out? I have seen them on Ebay, but have yet to get a set of either.
So doing them by hand, I understand you have to be careful not to cut too deep..? How do you measure the right depth? My machinist used a sharpie..
Re: Valve Seat Grinding and StonesWhen I first started to rebuild these engines I'd send the head to a shop and the customer paid $125.00 for the work.
I have up to lately used the HONDA steel broach holder and 4 steel broaches. All used by hand and the exhaust used 2 brioches and same for the intake. As yet I have never found a need to do the insides of the seat area as they/all have been bigger than the HONDA broach for that area is already too small to cut anything. I now use the Neway guides and cutters "use by hand" and don't need to push hard as I did with the steel HONDA broaches. I also have a SIOUX brand valve system which I grind the end of the valve stems flat and the contact area of the intake valve. Some seats need to have the tops cut down so the 45 degree can be centered at the middle of the vale face and I use a SIOUX shaft. stone holder and 90 degree drill head with a special fastener for the stone holder. I've acquired all these tools over time and now am able to do complete valve jobs and head rebuild for $125.00 which is less than what one can get the tools for. ......I have 2 heads in shop now and another on the way. Not much money for the work but "I'm doing heads". .................lm
John
Yes - the Neway cutters are by hand and are quite a big expense unless you have a few heads to do. You'd probably need to do three heads to get your money back. They have tungsten carbide cutting blades which are replacable and they cut quickly.  The 45 deg part of the seat is the important bit, and it needs to be smooth and free of pits. Therfore you need to get that part done, then try lapping the valve before checking the contact area. The deeper you have to cut, the farther out the contact area will be on the valve seat. If it is too far out you'll need to do a 60 degree cut to 'move' the contact area in a little. With the seat in from the edge of the valve (I check with "Engineer's blue) you need to check for the width of th econtact area. This is often quoted at 1-2mm. If it is too wide it will reduce the sealing pressure on the seat and if it is too narrow the seat may wear quickly. You can use the 30 degree cutter to open the port and reduce the contact area. I have the Honda cutters but, as LM says, they need more pressure than the Neway TC cutters. The cheap set from India is somewhere between the two. The High Speed Steel cutters cut nicely and the price is very keen at around $60 a set. I did a CB400F head recently with one of their sets and it worked pretty well. I tried some of the Honda cutters but the Indian set cut better. The CB400F shares the same 5.5mm pilot as the Honda 50/70/90s. When I was a kid I used to take my Triumph heads to a guy in a nearby village (he ran an Aston Martin DB5). He had the Black & Decker set which did a very quick job and he had to custom cut a stone for my seats. I cannot remember whether he did the three angles or not. I improvised a set up with a small grindstone to do a Honda 70 head. I turned down the arbor to 5.5 mm, cut the angle with a diamond dresser in an old lathe and made a flexible drive to a power drill using a motorcycle rubber handlebar grip and a 1/4 bolt....... :-)  I used something similar to do a BSA 650 head. I bought some stones but made my own arbor.  I love buying / making tools and learning the processes for myself...... :-) G
'60 C77 '60 C72 '62 C72 Dream '63 CL72
'61 CB72 '64 CB77 '65 CB160 '66 Matchless 350 '67 CL77 '67 S90 '77 CB400F
It's whatever floats your boat mate.
I use stones which I have had for many years. They were from my old mechanic days, and I also have the diamond tip tool to resize and recut angles on the stones as I need them. Still have a couple of original large unused stones in the kit. Considering the amount of time you can spend to get it just right, LM is doing it for a very good price, and you will be sure it's done properly. Cheers, Brian.
I thank you for the positive comment BRIAN. ...........lm
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