|
uh, oh -- post drill gear problem
I tore down old No. 97 today, wondering what was up with the feed handle.
It's a very simple feed mechanism -- a vertical shaft fixed from rotating by a keyway riding on a pin, with a rack machined into it. This part is in excellent condition with no apparent damage to the gear teeth. The mating part, however, is a 3/4" shaft with integral 12-tooth 12DP 14.5°PA gear with a very wide face, well over 1" wide. This is functionally identical to a wide 12-tooth steel spur gear mounted on a 3/4" shaft. The part of this shaft that is machined as a spur gear is pretty mangled. It isn't that the teeth are broken, rather in a couple places they have been overstressed to the point where the metal has flowed. I could just grind off the excess, leaving a very thin tooth, and it would once again go up and down smoothly, but it would transmit very little force. I don't have a 12DP 14.5PA 12 tooth cutter or I'd be looking at cutting my first gear. I priced out a steel spur gear, figuring I could just turn this gear off its shaft and machine a keyway and put on a replacement gear, but it looks like I'd need an extra-wide one which is too much $$. This whole machine isn't worth much even in perfect condition (a Champion No. 97 post drill with fast & loose flat belt drive pulleys) so it isn't worth putting a lot of dollars into. All of the spur gear teeth are badly worn, or I'd grind down the bad ones, drill and tap for some set screws, and cast new teeth out of JB Weld. But these teeth look like they have to take a pretty heavy load and I can't get a good casting anywhere on this gear, so that's out. Anyone got a spur gear excess to their needs? A gear cutter I can borrow? A better idea? I can post a pic if that would help. Grant Erwin Kirkland, Washington To email me see http://www.tinyisland.com/email.html |
On Sat, 26 Feb 2005 15:04:54 -0800, Grant Erwin
wrote: I tore down old No. 97 today, wondering what was up with the feed handle. It's a very simple feed mechanism -- a vertical shaft fixed from rotating by a keyway riding on a pin, with a rack machined into it. This part is in excellent condition with no apparent damage to the gear teeth. The mating part, however, is a 3/4" shaft with integral 12-tooth 12DP 14.5°PA gear with a very wide face, well over 1" wide. This is functionally identical to a wide 12-tooth steel spur gear mounted on a 3/4" shaft. The part of this shaft that is machined as a spur gear is pretty mangled. It isn't that the teeth are broken, rather in a couple places they have been overstressed to the point where the metal has flowed. I could just grind off the excess, leaving a very thin tooth, and it would once again go up and down smoothly, but it would transmit very little force. I don't have a 12DP 14.5PA 12 tooth cutter or I'd be looking at cutting my first gear. I priced out a steel spur gear, figuring I could just turn this gear off its shaft and machine a keyway and put on a replacement gear, but it looks like I'd need an extra-wide one which is too much $$. This whole machine isn't worth much even in perfect condition (a Champion No. 97 post drill with fast & loose flat belt drive pulleys) so it isn't worth putting a lot of dollars into. All of the spur gear teeth are badly worn, or I'd grind down the bad ones, drill and tap for some set screws, and cast new teeth out of JB Weld. But these teeth look like they have to take a pretty heavy load and I can't get a good casting anywhere on this gear, so that's out. Anyone got a spur gear excess to their needs? A gear cutter I can borrow? A better idea? I can post a pic if that would help. Grant Erwin Kirkland, Washington To email me see http://www.tinyisland.com/email.html Grant:\ Let me look in the tool box on Monday morning to see if I might have that cutter. Errol Groff Assuming of course that we don't get snowed out again! |
Well, I remembered another stack of cutters and one of them looks sort
of right. All it says on it (using a strong light and reading glasses) is: "8 14" -- so an optimistic guy might interpret that as a No. 8 cutter (12-13 teeth) with 14.5° pressure angle. Then again, it might not be. I hate it when I can't figure out what a cutter is. Anyone? - GWE Errol Groff wrote: On Sat, 26 Feb 2005 15:04:54 -0800, Grant Erwin wrote: I tore down old No. 97 today, wondering what was up with the feed handle. It's a very simple feed mechanism -- a vertical shaft fixed from rotating by a keyway riding on a pin, with a rack machined into it. This part is in excellent condition with no apparent damage to the gear teeth. The mating part, however, is a 3/4" shaft with integral 12-tooth 12DP 14.5°PA gear with a very wide face, well over 1" wide. This is functionally identical to a wide 12-tooth steel spur gear mounted on a 3/4" shaft. The part of this shaft that is machined as a spur gear is pretty mangled. It isn't that the teeth are broken, rather in a couple places they have been overstressed to the point where the metal has flowed. I could just grind off the excess, leaving a very thin tooth, and it would once again go up and down smoothly, but it would transmit very little force. I don't have a 12DP 14.5PA 12 tooth cutter or I'd be looking at cutting my first gear. I priced out a steel spur gear, figuring I could just turn this gear off its shaft and machine a keyway and put on a replacement gear, but it looks like I'd need an extra-wide one which is too much $$. This whole machine isn't worth much even in perfect condition (a Champion No. 97 post drill with fast & loose flat belt drive pulleys) so it isn't worth putting a lot of dollars into. All of the spur gear teeth are badly worn, or I'd grind down the bad ones, drill and tap for some set screws, and cast new teeth out of JB Weld. But these teeth look like they have to take a pretty heavy load and I can't get a good casting anywhere on this gear, so that's out. Anyone got a spur gear excess to their needs? A gear cutter I can borrow? A better idea? I can post a pic if that would help. Grant Erwin Kirkland, Washington To email me see http://www.tinyisland.com/email.html Grant:\ Let me look in the tool box on Monday morning to see if I might have that cutter. Errol Groff Assuming of course that we don't get snowed out again! |
Grant Erwin wrote:
Well, I remembered another stack of cutters and one of them looks sort of right. All it says on it (using a strong light and reading glasses) is: "8 14" -- so an optimistic guy might interpret that as a No. 8 cutter (12-13 teeth) with 14.5° pressure angle. Then again, it might not be. I hate it when I can't figure out what a cutter is. Anyone? - GWE Nope, in direct sunlight I can read more writing. It's a No. 8 cutter but for 14DP, dag nabbit. Close but no cigar. Still looking for a No. 8 12DP 14.5° pressure angle cutter. Grant |
In article , Grant Erwin
wrote: Grant Erwin wrote: Well, I remembered another stack of cutters and one of them looks sort of right. All it says on it (using a strong light and reading glasses) is: "8 14" -- so an optimistic guy might interpret that as a No. 8 cutter (12-13 teeth) with 14.5° pressure angle. Then again, it might not be. I hate it when I can't figure out what a cutter is. Anyone? - GWE Nope, in direct sunlight I can read more writing. It's a No. 8 cutter but for 14DP, dag nabbit. Close but no cigar. Still looking for a No. 8 12DP 14.5° pressure angle cutter. Grant I could rebuild the teeth with bronze, using TIG. |
On Sat, 26 Feb 2005 15:41:17 -0800, Grant Erwin
wrote: Grant Erwin wrote: Well, I remembered another stack of cutters and one of them looks sort of right. All it says on it (using a strong light and reading glasses) is: "8 14" -- so an optimistic guy might interpret that as a No. 8 cutter (12-13 teeth) with 14.5° pressure angle. Then again, it might not be. I hate it when I can't figure out what a cutter is. Anyone? - GWE Nope, in direct sunlight I can read more writing. It's a No. 8 cutter but for 14DP, dag nabbit. Close but no cigar. Still looking for a No. 8 12DP 14.5° pressure angle cutter. Grant I've read a lot of posts on the Yahoo shaper group about cutting gears with a hand ground single point tool. Got a shaper? Pete Keillor |
I have a buddy up here who owns my old shaper and has a real slick method
of making a single-point involute gear cutting tool. I just don't want to do all the work. I took a Swiss pattern file and sat in the sun the other day for about an hour and filed off all the places where the gear teeth were deformed into places they weren't supposed to be. Now it turns very smoothly. I'm planning to put old No. 97 back together and set it up as a sort of display item which could drill a hole e.g. in a board - but *not* a 1" hole through 1" steel, for example. A Champion No. 97 is a very cool old post drill. It is the kind that has 2 flat belt pulleys *and* the extra-cool Champion flywheel. The 2 flat belt pulleys are intended to be set up in fast and loose mode. The machine has self-actuated powerfeed down, manual retract, with lever-activated clutch. It also has 2 hand-cranked gear ratios, not just one. It's simply a lovely machine, too. Yet I don't want to go machining a complex precise pinion gear. I have enough problems, oops, I mean projects. I'm going to put this guy together enough so you can turn the handle and see it work, and move it and have parts not fall off, and then lean it against the wall until the next blacksmith's swap meet and then give somebody a good deal. Only way I'd even think of making the pinion gear is if I found a regular milling involute cutter. Grant Bill Fill wrote: Grant- Yes, it would be fun to cut the gear portion on a shaper. The toolbit could be ground to the shape of the tooth space as Peter points out. Also, it's possible to generate the involute curve by using a cutter with straight sides, shaped like a rack tooth, and rotating the gear under the cutter as the table traverses. Here's a picture of the setup, cutting a 10 dp 40 tooth steel gear: http://home.comcast.net/~b.fill/rg.jpg A similar setup is possible on smaller shapers, but space becomes limited: http://home.comcast.net/~b.fill/mg.jpg If you want to come down to Olympia to make your part, just let me know. -Bill Fill Olympia, WA "Peter T. Keillor III" wrote in message ... On Sat, 26 Feb 2005 15:41:17 -0800, Grant Erwin wrote: Grant Erwin wrote: Well, I remembered another stack of cutters and one of them looks sort of right. All it says on it (using a strong light and reading glasses) is: "8 14" -- so an optimistic guy might interpret that as a No. 8 cutter (12-13 teeth) with 14.5° pressure angle. Then again, it might not be. I hate it when I can't figure out what a cutter is. Anyone? - GWE Nope, in direct sunlight I can read more writing. It's a No. 8 cutter but for 14DP, dag nabbit. Close but no cigar. Still looking for a No. 8 12DP 14.5° pressure angle cutter. Grant I've read a lot of posts on the Yahoo shaper group about cutting gears with a hand ground single point tool. Got a shaper? Pete Keillor |
| All times are GMT +1. The time now is 03:28 PM. |
Powered by vBulletin® Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Copyright ©2004 - 2014 DIYbanter