Next Project Boring Head

mickri

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Now that I am done with the ER32 collet chuck it is time to think about my next project. A boring head. In the not too distant future I will need to turn some tapers. A boring head in the tailstock would provide the necessary offset so I could turn the tapers between centers. I have been looking at DIY plans online. The attached plans are representative of what I have found. One is your typical round boring head. The other is a rectangle. I have stock on hand that I could use to make either one. I also found this thread on making a rectangular boring head. https://www.hobby-machinist.com/threads/shop-made-boring-head-project.22120/. I found this thread very interesting because he used an end mill to cut the dove tails. I don't have a dove tail cutter and would have to buy one. I was reading a website about making a boring head where it was stated that dove tail cutters are easily damaged. No experience with dove tail cutters but I have damaged end mills making the tool holders for my Norman style tool post.
All of the boring heads that I have seen use dove tails. Is there a reason for this? Why I ask is that I have a key way cutter and could make a T slot instead of a dove tail. Here is a rough sketch of the body. Seems to me that this would be easier to make than dove tails. If you guys think this has merit I will do a detailed sketch. Because it seems to take me forever to get something done I should get started on this sooner the better.

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Attachments

  • boringhead.pdf
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  • Boring Head 02.pdf
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I think the advantage of the dovetail is that either using a tapered gib, or more commonly on boring heads a split dovetail with adjustment screw, you can take out all the slop without an extremely high level of accuracy in the machining. The dovetail has a single adjustment that takes out play in the axial and radial directions, while a T slot would need two. That being said, I don't see any reason you couldn't make a boring head this way.
 
If you observe cutting speed and feed limitations, there is no reason to fear using a dovetail cutter.
 
Making a dovetail cutter, based on a triangular insert is a very doable home project. I did. I found that it cut slowly (a single tooth cutter banging away) - but the result was great. My application was the DTs on Aloris style QCTP holders.
 
I made the one in the 2nd PDF file you show recently, it's not a real difficult project and works very well....
The first one you show looks like another project for me down the road............:grin:
 
I am going with the rectangular boring head shown in the 2nd PDF. I cut two 2 1/4" long pieces off of a chunk of 2" x 1 1/4" 1018 steel this afternoon. It's a start. Probably won't get back to it until next week. Have other projects on my plate that will take up the rest of the week.
 
If I decide to use a dovetail cutter instead of an end mill to cut the dovetail what size dovetail cutter should I buy?
 
Had some time today and was able to true up the ends of the pieces that I had cut with my trusty hacksaw. I also like to make a 3D drawing. I use google sketchup and have found that doing the drawing gives me a good idea of the order of the steps I will have to take to make something. Here's my drawing of the two main parts.

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Two things that I am wondering about. One is what size boring bars should I drill the holes in the head for? I don't have any metric drills and my imperial drills are in 1/64 increments. I am leaning towards 1/2" boring bars. Other choices under consideration are 3/8, 10 mm & 12 mm.

The other thing is the piece that the lead screw screws into. Several questions here. First is how precisely does this piece have to fit in the slot. The plan that I am loosely following has a .60 wide slot with a .46 wide piece. This leaves .007 clearance on each side. That would be a sloppy fit imho. The piece in the plan is rectangular being .46 wide by .62 long. With the sloppy fit I don't think that it provides much if any guidance as the boring head moves back and forth. In looking online I have also seen this piece being round. In the thread I referenced in my first post this piece is also round. A round piece would be the easiest for me to make.

I want the shank to be round. I have an ER32 collet chuck that lives in my mill/drill. I also have an ER32 collet chuck with a mt2 taper that pretty much lives in the tailstock on the lathe and an ER32 collet chuck for the lathe spindle. With a round shank the boring head is usable in any of the ER32 collet chucks.

With a round shank and a round piece for the lead screw I could make the shank long enough to extend through the base to serve both as the shank and for the lead screw.

boring head plan 2 with shank.jpg

Then the question becomes how to attach the shank to the base. My initial thought was to drill and tap a hole or two through the base and the shank for a bolt or machine screw. I have also thought of using roll pins. My concern is sheering off the bolt or roll pin when using the boring head in the mill. The shank would be 1/2" with probably 1/4" bolts or roll pins. The plan uses four 1/4x20 screws to attach the shank to the base. Would this work?
 
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