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Boucher
07-08-2010, 09:36 PM
I would like to turn a 5 internal taper that is longer than my cross slide travel. My cross slide moves about four inches and I would like to turn an internal taper that is about twice that long. My brain has gone into lock down.
Is there a way to do this?

becksmachine
07-08-2010, 09:47 PM
I would like to turn a 5 internal taper that is longer than my cross slide travel. My cross slide moves about four inches and I would like to turn an internal taper that is about twice that long. My brain has gone into lock down.
Is there a way to do this?

Are you maybe referring to the travel on your compound rather than the cross slide?

Dave

spope14
07-08-2010, 09:53 PM
How ling, what mouth and end diameter? Done this a few times with diameters of fair size with longer bore bars. always had to blend things in and keep everything all chucked up and the angles set up right. Good dykeming to create the blend and sand it all up afterwards real nice at the blend line.

If you have a mating gauge, some prussian on the gauge helps blend things in as well.

Forgive my typing, going one handed at it at the moment.

loose nut
07-08-2010, 10:39 PM
A taper attachment would be best but since you are asking for a method I'll put 2 and 2 together and say you don't have one.

What spope said, I have had to use this method and it works, you just have to be careful when you are about to match the two parts of the taper so that it looks like one.

fasto
07-08-2010, 10:49 PM
Do you actually need 8" of taper, or would two sections a few inches long at each end suffice? You'll probably notice most commercially made tapered things don't have a continuous taper unless they're pretty short. Things like MT3 arbors, for instance, often have a relieved section in the middle about half their length.
If your application can work with this, there's no need to blend the taper. Just cut the middle section a bit deeper. Of course you'll have to get the front & back usable tapered sections properly in line!

The Artful Bodger
07-08-2010, 11:00 PM
How about a boring bar with two, or three cutting tips on it, space them about 3" apart and set them up so they are all turning the same diameter.

Boucher
07-09-2010, 11:44 AM
I am playing with the nozzle design of a naturally aspirated forge burner. I am starting with Ron Reids Burner and just trying to get a feel for how it works. I have a stainless expansion section attached to 3/4" pipe. I am boring this by setting the compound slide to slightly less than 5 and using a boring bar to turn the internal taper.
http://i109.photobucket.com/albums/n50/boucherbyron/IMG_0111Small.jpg
The maximum travel of my compound slide is 4". I wanted to be sure that I wasn't overlooking a simple way to turn a longer section. Sorry about the use of the wrong term (cross slide) in the originall post. Having lots of brain *arts these days.

oldtiffie
07-09-2010, 12:01 PM
Byron.

Simple problem with a simple answer.

If you have two or more accurately-sized steel balls and a good depth micrometer you can use simple geometry, trigonometry and maths to measure the taper angle and the diameters of the taper.

See Machinery's Handbook 27 page 715 under the heading of
Angles and Tapers".

oldtiffie
07-10-2010, 04:50 AM
Byron.

How did you go with that internal taper?

The Artful Bodger
07-10-2010, 04:54 AM
I hope he tried my three-tooth boring bar idea!:)

Peter.
07-10-2010, 06:32 AM
I am playing with the nozzle design of a naturally aspirated forge burner. I am starting with Ron Reids Burner and just trying to get a feel for how it works. I have a stainless expansion section attached to 3/4" pipe. I am boring this by setting the compound slide to slightly less than 5 and using a boring bar to turn the internal taper.
http://i109.photobucket.com/albums/n50/boucherbyron/IMG_0111Small.jpg
The maximum travel of my compound slide is 4". I wanted to be sure that I wasn't overlooking a simple way to turn a longer section. Sorry about the use of the wrong term (cross slide) in the originall post. Having lots of brain *arts these days.

Why not use a dial gauge to set the face of the boring bar holder exactly parallel to the compound travel, then rough-out your taper and finish it by starting at the front, then when you run out of compound travel wind it all the way back and slide the bar through. Should be plenty good enough for a burner nozzle.

tmc_31
07-11-2010, 10:13 AM
Byron,

Have you had any success turning this taper yet? I need to do a similar internal taper with the same machine limitations you seem to have. I am interested in what method you used. I kind of liked Peters idea. Looks to me like you could step bore the shaft to get it close to the desired taper and then finish it out by sliding the boring bar forward in the tool holder as he describes.

Let us know how it came out.

regards,

Tim

Boucher
07-11-2010, 12:00 PM
For the 3/4" pipe burner the 4" taper is about the limit for extension of a boring bar that will fit into it. The burner is sputtering and I am not sure if this is due to the orientation of the orfice or flow separation from the wall. I need to experiment with it a little more.

I probably will try a larger size. The guys that are selling these type burners indicate that they spent large amounts of time developing them. I may just buy one of theirs. I am also experimenting with blown type burners. For what I want to do that may be a better way to go.

Quite by accident a supplier shipped some inserts that I ordered to a CNC shop that is nearby in the rural area. I was unaware they were here. I may get them to make some parts for me.

fishfrnzy
07-11-2010, 12:25 PM
I like Artful's idea and her's another.

What about getting a longer bar, set up you taper with 4" of overhang, bore as deep as you can, back up your compound, then extend bar another 4" and repeat. Would chatter more as you extend. Probably need alot of spring passes.

Chatter might get ugly with either of these but they may work.

Paul Alciatore
07-11-2010, 01:47 PM
I'm not sure how your burner works, but if the taper does not have a machinned, mating part, then even an approximate match in a two part taper should be good enough.

You could almost eyeball it. Turn the first four inches then put some blue marker or magic marker ink on the inner 1/2" of it and turn the next 3.5" down until you scratch that marker. Repeat for a third section is necessary. If you need to blend it better, use fine sandpaper on a small wood dowel or metal round.