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| raynerd:
Hello, I`ve not posted on here in a while. My clock is running but I`ve had some problems, I (my wife!!) smashed the three glass dials that I had water jet cut and I can`t afford these to me remade until after Christmas. I also gave up a little on the woodwork and a friend of mine is now onto building a case for me. So I`m having a break and I`m trying to repair a Synchronome clock that I purchased a month or so ago. I need to make the pallet using the following plans here: http://raynerd.co.uk/wp-content/upLoads/PalletMachined.pdf I really can`t get my head around the machining process. I can obviously start by machining up a solid block of brass to maximum dimensions and then I guess start by drilling the top centre hole but I`m not sure where to go from there. I am particularly stuck on the best method to cut the radius concentric with the centre bore as shown!! Don`t get me wrong, I`m sure I could plunge into cutting this down, whittling in a trial and error method, but I`d like any suggestions as to the best order and the best machining methods. There seems quite a lot of new faces on here from when I was posting in the last months and so just to recap, I have a Boxford Mod A and an X2 mill with cnc rotary table for my use! Any help or suggestions would be welcomed. Chris |
| sparky961:
If I saw that part come across my desk for quoting, I'd decline to quote. :P As for process, I'm sure others will chime in but I think "whittling" is the right idea. Certainly multiple setups, I'd think, done very carefully to avoid any stack-up errors. As for the interestingly-shown radius, why not leave that until last and clamp the part onto a rod chucked in the lathe? It seems pretty clear this is the intended purpose of the vertical hole and slit anyway. You could either cut the profile with CNC if available, or with a ground form tool, nice and slow. I'd either leave the slit until second last or make sure you have something that fits snug so that you can keep clamping on the front/back without the part deforming. Before that, a 3/4" ballnose endmill for the 3/8 rad, some angle blocks to set it on while you machine that top angle, but make sure that you cut the sides with a straight endmill and those chamfers with a chamfer mill before cutting the top angle off (they didn't do you any favours by not including the angle, by the way) - that way you can still lay the part on it's side. Probably want to drill those freakishly small holes while it's there too. Seems to me a few dimensions of the "body" part are missing as well. That certainly doesn't help matters. I'll see about some pictures to illustrate what's in my head... -Sparky |
| sparky961:
Ok, a bit more thought and here's the order that I'd attempt it if I were doing it myself.... Machine your block to overall dimensions: Clamp laying down in vice on parallels, use end mill and chamfer mill: Flip and do the same on the other side. Drill your freakishly small holes while it's laying down this way. Tap them before you get too far along as well: Stand part up in vice, gripping on thinner section and cut radius with 3/4" ballnose (or whatever is at hand, as many wouldn't have one of these) Same setup, drill/ream the vertical hole: Lay flat again, use slitting saw to cut the slit: Place on angle block or whatever you come up with to set the part at the same angle as the top should be milled. Again, clamp on the thin section and hang the "body" out the side of the vice. Depending how floppy it is and how heavy you want to cut, you may have better success clamping on the main body using a 3/8" rod in the vertical hole so it doesn't compress: Clamp to a 3/8" rod, chuck in a lathe and use a ground form tool with the correct radius. Or use CNC to profile the radius: How did I do? :) With a bit more thought, the number of setups might be less but this seems a pretty step-by-step foolproof way. -Sparky |
| sbwhart:
Wow thats interesting. First thing you have to do is study the job and ask yourself what does it do what are the critical to function features, looks at the drawing I'd say these were curved radius that the drawing shows being made like do nut on the 1.296 rad the designer wouldn't have draw it like that unless it was important. So I'd make it out of a of a slice of 3" dia bar, drill and ream ,313" bore and mount the slice on a mandrell made to fit the job, then I'd swap the chuck over to the RT on the mill and with a .75mm end mill find the corect location for the centre of the rad and generate it using the end mill. Getting these features correct I guess would be the most important job the rest could be hacked out as best you can and making it out of a slice you'd get more than one go's at it. If you didn't fancy doing it in the RT you could grind youself up a .75 form tool and form the rad on the lathe but getting it in the correct position would be dificult. Stew |
| DaveH:
Sparky, Nice :clap: :thumbup: :beer: DaveH |
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