Model Engine Maker
Help! => Hints, Tips & Tricks => Topic started by: 90LX_Notch on July 26, 2012, 12:52:36 AM
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I originally posted this at the other site.
It's how I machined the bottom radius of the crankcase for my build of Gail Graham's Lobo Pup Twin.
The video description on YouTube describes what is going on. It should be noted that the bulk of material was removed in the mill prior to this operation. This is more of a finishing op.
The Dremel FexShaft is held in a tool block that was bored on center with the lathe. I plan to post up some pictures of the the block in another thread.
Any questions just ask.
https://www.youtube.com/watch?v=EXw-VoGucOg
Edit- I copied the description off of YouTube-
"This video shows a crankcase being machined on the lathe with a Dremel Flex Shaft. The crankcase is on an arbor and is being indexed by hand. The 1/8 endmill is set on center and is cutting on the tangent point of the radius. This was an experiment that worked out far better then I had hoped."
-Bob
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great one more thing i HAVE to remember :facepalm:
really thanks bob that is a good one, and thanks for the video :bandrock:
chuck
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Wow, is that ever slick. Sounded really good too.
After roughing, did you make a few finishing passes?
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I've done a lot of this sort of incremental machining. I like to refer to it as HAM - Human Assisted Machining. :Jester:
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Here's another one of those "Why didn't I think of that?" threads. I'm constantly amazed at what I haven't thought of. Sometimes I think I could fill a book with what I don't know.
Marv, was that an emoticon you just used there? :stir:
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Yes, Dennis, I broke down and used an emoticon. Not just an emoticon, but an animated one - my personal bete noir.
I had just finished writing a long discourse on another subject and my word bank was empty so I had to resort to using one of the crutches for the inarticulate. It still pains me. I'm searching for my hair shirt as I write this.
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I can't find any hair shirts, this being about the closest: (http://www.silkysteps.com/forum/images/smilies/Viannen-(c)-itchy.gif)
I reckon this one fits the bill better, based on your description: (http://www.silkysteps.com/forum/images/smilies/feather.gif)
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Kevin-
The video basically shows the finishing passes. The bearings in the FlexShaft are less then desirable; so very light cuts must be taken to prevent chatter. It's time consuming; but, it sure beats filing! The trick is to scribe a line and rough to it as much as possible in the mill. The Dremel basically replaces a file in smoothing/blending the profile.
-Bob
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I did some similar profiling using a RT mounted vertically on a mill. Much the same process: the RT is vertical with its axis in line with the X axis. The end mill is set on the center line of the rotation and the majority of the shaping is done, leaving enough angle on each side to avoid undercutting. To finish up, the end mill is offset by its radius in Y. That allows the cutter to finish the 90 degree swing to one side without undercutting the part. Offset the end mill in the opposite direction and finish up the cut on the other side.
Of course if you are shaping to other than a circle this won't work.
Alan
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I don't have a RT; so this was the only method I could come up with for the bottom radius. A RT is on my wishlist; it would make life easier.
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Nice Bob! What other place? :NewBrain:
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Nice job. Maybe it could be done on a Spindexer as well? Got any pics of your grinder setup, it's on my "to do" list ... ;)
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Dave- I originally posted this in July and was referring to that "other" site that a bunch of us left.
Arbalest- I'll take a picture and post it up. It's a real simple tool block made from scrap aluminum.
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Dave- I originally posted this in July and was referring to that "other" site that a bunch of us left.
Arbalest- I'll take a picture and post it up. It's a real simple tool block made from scrap aluminum.
I know Bob....just kidding..... ;D
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Arbalest-
The Dremel is hung above the lathe and the FlexShaft runs through the tool block. When I made it, the face of the block near the headstock was indicated and aligned with the cross slide. The bore in the block was then machined in the lathe so that it was on center with the lathe and perpendicular to the aforementioned face.
I originally made this so I could accurately spot bolt circles in the lathe with a center drill. The profiling idea came out of necessity(desperation).
Any questions, feel free to ask.
-Bob
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I see now that I am going to have to dig my Dremel out and make a holder for it. I also have a Roto-Zip that is an extra and I may be able to use.
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Dremel has been bought by Bosch and greatly up-scaled, so the bearings on the new ones may be better than old.
This is a terrific way to finish. Damn, another one on the list.
Mosey
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Continuing the box exterior thinking...
With the advent of QCTPs, those of you with Unimats might want to consider making an adaptor that allows you to mount the Unimat power head to the tool post. I've considered it for a long time but all the tuits I have are square.
Since the Unimat head is made to do milling, this would obviate the bearing problem.
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Continuing the box exterior thinking...
With the advent of QCTPs, those of you with Unimats might want to consider making an adaptor that allows you to mount the Unimat power head to the tool post. I've considered it for a long time but all the tuits I have are square.
Since the Unimat head is made to do milling, this would obviate the bearing problem.
Me too, Marv. It sure looks like a tool post grinder to me!
Jerry
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Or you could beef it up a bit and use a die grinder, I made a really rigid post to hold mine on the myford.
It also takes larger diameter cutting tools as well which gives a bit more choice.
(http://i456.photobucket.com/albums/qq286/pgp001/Model%20Engineering/Various%20Tooling/Alexander%20Mill/PICT3612_zps3f507341.jpg) (http://s456.photobucket.com/user/pgp001/media/Model%20Engineering/Various%20Tooling/Alexander%20Mill/PICT3612_zps3f507341.jpg.html)
(http://i456.photobucket.com/albums/qq286/pgp001/Model%20Engineering/Various%20Tooling/Alexander%20Mill/PICT3613_zpsce7b1380.jpg) (http://s456.photobucket.com/user/pgp001/media/Model%20Engineering/Various%20Tooling/Alexander%20Mill/PICT3613_zpsce7b1380.jpg.html)
Phil
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Phil
Just out of curiosity, what sort of Metabo hand tool is that? Did it come with such a long neck?
Vince
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Without going to the workshop to look at it I cannot tell you the exact model number.
But yes it did have a long parallel neck as standard, I chose it for that reason and the fact that the motor housing is offset to one side.
That gives a lot more clearance when using it near the lathe tailstock.
I dont think I paid more than about £60 for it brand new on ebay, but I have had it a good few years now.
I also use this for cylindrical grinding as well.
I designed and made this new grinder head for my Union tool and cutter grinder, but made it also fit the Myford cross slide at centre height whilst I was at it.
(http://i456.photobucket.com/albums/qq286/pgp001/Model%20Engineering/Simplex%20Petrol%20Engine/SimplexEngine009.jpg) (http://s456.photobucket.com/user/pgp001/media/Model%20Engineering/Simplex%20Petrol%20Engine/SimplexEngine009.jpg.html)
(http://i456.photobucket.com/albums/qq286/pgp001/Model%20Engineering/Simplex%20Petrol%20Engine/SimplexEngine019.jpg) (http://s456.photobucket.com/user/pgp001/media/Model%20Engineering/Simplex%20Petrol%20Engine/SimplexEngine019.jpg.html)
Just so we don't wander to far off topic, here is an early photo of my set up for cylindrical grinding with a dremel (actually its a Proxxon)
I occasionally restore antique cylinder musical boxes amogst other things, this is the setup for finishing the outside diameter on the pin tips of a newly re-pinned musical box cylinder.
(http://i456.photobucket.com/albums/qq286/pgp001/Model%20Engineering/Musical%20Boxes/Cylinder%20Pin%20Grinding/10497pingrinding01_zps58fecce7.jpg) (http://s456.photobucket.com/user/pgp001/media/Model%20Engineering/Musical%20Boxes/Cylinder%20Pin%20Grinding/10497pingrinding01_zps58fecce7.jpg.html)
(http://i456.photobucket.com/albums/qq286/pgp001/Model%20Engineering/Musical%20Boxes/Cylinder%20Pin%20Grinding/10497pingrinding02_zpsaf3500a7.jpg) (http://s456.photobucket.com/user/pgp001/media/Model%20Engineering/Musical%20Boxes/Cylinder%20Pin%20Grinding/10497pingrinding02_zpsaf3500a7.jpg.html)
Those photo's must have been taken more than ten years ago, as it was my old Myford ML7.
Phil
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How interesting. I'd never considered re-pinning music box cylinders before.
Hugh.