Milling Circular Arcs By Cnc

[Dave T]

I have been making fly reels by manual operation of a mill and lathe, and am trying to decide if CNC would also work.
As a new member, it appears that I cannot insert a photo here (because it might be spam?). But look at my Avatar for an aluminum frame reel, or click on the attached image file to see a bronze frame reel.
Consider the front end ring. It is a thin ring that is supported by several lugs. I cut the arcs between the lugs with my mill and a rotary table. The finish is smooth enough that the part only requires tumbling in stainless steel media to finish.
If I made this part on a CNC mill or router with X, Y, and Z axes, and used the appropriate G code to cut the arcs, could I achieve the same finish? Or would a rotary table still be needed?

 

[Karl_T]

piece of cake on a CNC mill

 

[JimDawson]

Welcome to The Hobby Machinist Dave. We require five posts before allowing content beyond plain text to keep the spam under control, sorry for the inconvenience.

That is a very CNC-able (a new word) device. The finish would be a function of the tooling and the rigidity of the machine. An inexpensive router will be less ridged than your mill. You could also do the hole pattern on the spool very easily on a CNC also.

Very nice looking reel!
.
.

 

[kd4gij]

There was a member here a couple of years ago that makes fly reals an a g0704 converted to cnc. But I haven't seen him on in a while.

 

[RJSakowski]

A good CNC will do a very reasonable job of machining a true circle. There are some small deviations due to lost motion, response time, etc. When I was shopping for my Tormach, I asked the sales rep. why I needed a boring tool if I had a CNC. His response was that there will be some inconsistencies and if you want a truly round hole, you will use a boring tool. That said, I have machined a good many holes using circular pocketing routines and never had any issues with them.

If you can live with .001 to .002" tolerances, A CNC mill should work very well for you.

BTW, Welcome to the group and a very nice fly reel!

Bob

 

[Dave T]

Guys,
Thanks for the responses. What I conclude is that I will probably need a motorized rotary table in addition to X, Y, Z axes.
There is very little in the reel that needs tolerance better than .002, and quite a bit that could be done at .005. What is needed, however, is a smooth, clean appearance on the visible surfaces. The customers for my reels are guys who make split bamboo fly rods, and they do beautiful work. They go to great lengths to be sure that no speck of dust gets into the varnish.
If the OD of the front end ring were cut by alternate motions of X and Y as small as .0005, I think that the appearance would be quite flawed, optically. I would have no choice but to try to fix it with a hand file. Some guys do nice work with a hand file, but I am not one of them.
Dave

 

[Karl_T]

At least for these parts, no need for a motorized RT.

Sounds like finish is critical. This means you need a rigid machine. The very low end machines will likely not meet your needs.

If this is just a business for you, I'd buy the parts from a pro CNC shop. Of course, nearly all of us here want to say, "I made it myself". In that case, start shopping for CNC mills.

 

[RJSakowski]

Guys,
Thanks for the responses. What I conclude is that I will probably need a motorized rotary table in addition to X, Y, Z axes.
There is very little in the reel that needs tolerance better than .002, and quite a bit that could be done at .005. What is needed, however, is a smooth, clean appearance on the visible surfaces. The customers for my reels are guys who make split bamboo fly rods, and they do beautiful work. They go to great lengths to be sure that no speck of dust gets into the varnish.
If the OD of the front end ring were cut by alternate motions of X and Y as small as .0005, I think that the appearance would be quite flawed, optically. I would have no choice but to try to fix it with a hand file. Some guys do nice work with a hand file, but I am not one of them.
Dave

A CNC mill does not cut by alternate motions of the x and y axes. They are running simultaneously at proportional rates to give the required direction of motion. However, with any milling process, you will have scalloping because of the nature of the cutting action and the tool. This can be minimized by slowing the feed rate and increasing the rpm for the finishing cut. The CNC should also run at a constant feed rate so the milling pattern should blend consistently from the ring feature to the tab features. A rotary table will not give you that flexibility.

For good finish, it is hard to beat turning on a lathe though.

What the CNC mill will do for you is to automate the machining process and the permit machining multiple features in a single part setup, thereby improving registration considerably. It also will produce identical parts, important in a production environment and allow you to walk away from the process, improving your production efficiency.

Bob

 

[jeffecc10]

Dave what an awesome looking reel. Now I don't know about flimsy cnc. I run cnc lathes and mill every day. The machines we have are very good. So if you have a good cnc mill. You can bring your production of the that awesome fly reel to another level. The contours should be excellent. Beyond that you can produce your reel in a new way. You would need to sit down an rethink your process. Your should be able to reduce the time it takes to make your reel substantially. You would also be able to control your part size an overall quality much better. You can go from one at time to batches at a time and all of them being almost identical. If you don't have a cnc background it would be a good idea to get with someonr that does and go through your reel and come up with a process that wills work well with a cnc. If you have some small cnc shops in your area stop in talk with the owner. A lot of those guys are great and can give you some pointers. Anyway nice reel and good luck



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[countryguy]

Very cool project! I'd love to see how it comes out! The note on the scalloping is interesting. Could you use a real small end mill to minimise that? Say 3/16? or would you go large? I wonder how these would look from a Plasma CNC cut setup?