Gallery, Projects and General > Project Logs
Clock wheel cutter
raynerd:
If you do find any links Bernd that will help then please post them. I can do a google search myself and have done many but none seem to be specific to my issues and setup. I have spent hours and hours, if not days searching for clock wheel cutting over the last months as well as aquiring many books and emails containing specific scans of pages of books. Research is not lacking, it is understanding.
Would appreciate any video links - haven`t found many of use.
This is an escape wheel but he feeds in the Y-axis as I did:
This feeds into the X axis:
&feature=related
Chris
Bernd:
--- Quote from: craynerd on October 30, 2009, 04:49:23 PM ---Research is not lacking, it is understanding.
Chris
--- End quote ---
Well then practice, practice till you get it right. With all that information that you've gathered it's going to take some time till you get the "knack" of cutting clock wheels. Rome wasn't built in a day, right?
Bernd
raynerd:
I`m a bit lost with what your saying Bernd :poke:- I am practicing hence the wheel I`ve cut and all the information I`ve posted in this thread. No point going hell for leather at another wheel and wasting more brass without asking for advice as to where I could have gone wrong?
Anyway .....
I`ve just been speaking to someone who is a clock repairer and although he agrees that I have had issues with either the profile or height setup of my cutter (and so the wonky teeth) he said that the problem with my cutting is down to the brass I have used, apparently it is "sticky" plate brass- NBG and I need to use engraving quality leaded brass and cut in one pass. Now I need to order some spare cz120 brass!
Chris
bogstandard:
It looks like you have a few noticeable problems.
Your metal must be some sort of soft brass alloy, it surely isn't the hardened brass that a wheel of this type would be made of.
Your cutter is either blunt or doesn't have the correct clearance angles on it. As brass can usually get away with zero top rake, I would definitely suspect it being blunt. It needs to be honed to an edge that you could shave with.
On the first vid, it seems as though he is plunge cutting, but I suspect he is actually feeding the cutter in on the X axis as well, and only putting the cut on the Y. It is very difficult to see as the X axis movement would be very small. If you notice, he took well over a couple of minutes to cut the tooth. It has to be done slow and steady just as he showed. So for a 30 tooth gearwheel, over an hour to cut.
With regards to tooth positions, it looks almost certain that your blank or arbor has moved somewhat, due to cutting pressures.
Bogs
raynerd:
John, really appreciate the reply. I didn`t realise that it should be that sharp, I thought sharp was just a clean front edge! How would I achieve such a sharp edge .... people talk about having sharp HSS lathe tools and it is the same there, I thought it just means a good clean cutting edge.
Regarding the process of taking the cut, I`ve spoken to a few people tonight and believe the best way to do this is to feed along the X-axis and take the entire cut very slowly but in one pass. This is the information I was given and I hope that Jim doesn`t mind me passing this information on:
Reading the information I have been given on here and in the message below, I think I have fallen on a few accounts...
Chris,
Really nice job of documentation on your blog. And congratulations on your first wheel, be it a bit less than perfect. I don’t think my first one was perfect either.
To your questions, I have cut many hundreds of wheels and pinions, so I will comment on what works for me and my thoughts as to where you may have gone a bit wrong.
1. It looks to me as if you cutter is not really “sharp” as in really sharp - as john mentioned above
a. Is it very hard? If not, it will be difficult to sharpen and will give you ragged teeth like you are getting
2. I feed from the X axis into the cutter rotating into the gear blank
a. I cut full depth in a single pass (if and when I measured it well and set it up properly)
3. I use coolant/lubrication . I realize there are many books that say it is not necessary, I think a lot of writers have not cut very many gears. Yes it is messy.
4. I suspect you may not have a “free machining” brass. Some brass formulations cut far better than others. I use ˝ hard engraving brass for all my work and have for a very long time. I have tried some surplus brass that originated in China that was nearly impossible to machine, just FYI, even with coolant /lube and sharp cutters
5. Both wheel and pinion cutting likes a very rigid mount for both the blank and the cutter
6. I back up my blanks with either scrap aluminum or brass
7. I use fly cutters only as a last resort, but they work fine when the other 6 points above are in order
8. Cutter speed for fly cutting should be fast….. it is hard to rotate the cutter too fast on most mills…..I would push for at least 1500 rpm minimally
9. Feed rate should be slow into the cutter
Quite scary actually - reading all the above I think I have issues or done things incorrectly in nearly all aspects.
Time to try again....
Chris
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