Sportster rebuild.

[WJH]

You know, 95% of Harley's from the factory are still on the road.
5% made it home.
Sorry

[Patio]

I mounted my flywheel on my lathe, in the 4jaw chuck. I was having a heck of a time getting it dialed in, well enough to make me happy, and I am not confident in how well it all holds. After a bunch of thinking about things, it came to me! I need to mount this in a three jaw chuck with soft jaws! That would allow me to get things concentric and perpendicular to the axis of the lathe.

Soooooo, today I ordered a 6" backing plate to fit the threaded spindle of my lathe. While I wait for it to arrive, I will make some soft jaws for the three jaw chuck that came with a dividing head, I have. This will make things much easier, and I will have a 3 jaw scroll chuck for the lathe. Later I will make an adapter to be able to mount either the 4 or 3 jaw, to the dividing head, leaving the existing backing plate on the 3 jaw, as a face plate for the dividing head. The best of both worlds!

More to come as the plan progresses on!

[Harold_V]

Chuckle!
The wisdom of soft jaws appears to be obvious to you, Patio. I wonder how many still don't grasp the significance of their use?

In this particular case, so long as the only thing you must do is face the flange (as we discussed by phone), soft jaws will be more than adequate. However, there's more than a small chance that if the tapered bore must be addressed, that the piece will still require chucking with a four jaw. Everything depends on how concentric the bore is with the OD.

Harold

[Patio]

Tonight's work in the shop.

Started making the soft jaws. I am using some plate steel, the use to belong to and exerciser machine. My horizontal band saw is still up at a friends place getting repaired from me breaking the hinges out of it, so I used a portable one that I have for my day job.

Here are the pictures, cause everybody loves pictures, me included.
I am using the one on the left, the one on the right is an intact piece as I got it.

The tools used for holding and cutting.

After a run through the mill to get to rough size.

Now I need to make a plan, for the cuts.
Make a plan, or plan to fail.
It is nice to get some time on the milling machine, as I have not used it much since it arrived.


I don't know how much I will get done this weekend, as the woman likes going to a friends place on the river, over the holiday.
Happy wife! Happy life! So tomorrow is get the camper ready, after work.
I wish all of you a wonderful weekend!
More to come.

[Patio]

The plan! or at least a drawing.

These measurements were taken with a, cheap digital caliper. I also have not done any addition of measurements for proper totals.
The critical measurements, are those of the bottom, and they are only critical in the relationship with each other.

Next week, we will see how it goes.

[Patio]

Tonight's progress.

I have the bottom sides of the soft jaws cut on the mill.

Here are the pictures.

This is a picture of a stop that came with the mill, that the PO had made. There is a pair of them, one end is a 90 and the other a 45.

The second, stop, of the pair.

Now I need to drill and counter bore, two holes in each one, rough mill the other side, turn the new backing plate, that arrived today, mount chuck, and turn jaws for flywheel.

With that said, I have a dilemma. I do not own any counter boring bits.
If I drill the through hole first, can I run an end mill down the center of the hole, and expect it to stay pretty much concentric, with the original hole?

More to come.

[Harold_V]

If I drill the through hole first, can I run an end mill down the center of the hole, and expect it to stay pretty much concentric, with the original hole?

Yes, but make sure you lock the saddle and table, and don't try the counterbore without setting a spindle stop, in case the end mill hogs. Don't crowd the cut, as an end mill is side cutting (as you know) and will readily cut oversized if one flute loads. Not as likely to happen if you predrill the bolt hole, however.

Remember, the counterbore isn't intended to act as a guide---just a relief for the head of the screw. Heads are not always concentric with the pitch diameter, so make the counterbore slightly larger than the head of the cap screw.

You can also grind (by hand) flat bottom drills. The problem with them is they require a full diameter pilot hole, so the size of the counterbore is generally drilled with a pointed drill, staying shallow, then the hole cleaned out with a flat bottom. I did that routinely, purposely avoiding the use of counterbores due to the problems that are inherent with using such a tool. It's all too easy to break the pilots.

Because drills are generally quite long, as a flat bottom tool, they won't cut without deflection. It is for that reason that one predrills the counterbore to full diameter, so the margins of the drill can engage the created hole, at which time they can be used without issue.

Harold

[GlennW]

Keep in mind that an end mill will not cut a flat bottom hole or counterbore when plunged due to the relief.

The bolt head will only have contact right at the circumference of the bolt hole.

[JackF]

Harold and Glen,

One again, another lesson learned. I don't have any counter bores so I have just used a end mill of the proper size right after drilling the through hole. I never thought of using a flat bottom drill to make the counter bore. I knew that the end of end mills were relieved but never took that into consideration. This is such a great learning site.

Jack.

[Harold_V]

Harold

Harold and Glen,

One again, another lesson learned. I don't have any counter bores so I have just used a end mill of the proper size right after drilling the through hole. I never thought of using a flat bottom drill to make the counter bore. I knew that the end of end mills were relieved but never took that into consideration. This is such a great learning site.

Jack.

The issue with the bevel isn't critical, in particular if the hole is chamfered after the counterboring operation. The resulting seat will quickly assume the contour of the head of the cap screw. It often isn't a true 90° surface, anyway. By chamfering the hole, none of the material gets displaced, tightening the hole on the screw.

As far as flat bottom drills are concerned, I used them routinely in my years of tool making. They are heads and shoulders better than counterbores, although they must be used with care, as they are not capable of starting a flat bottom hole unless the drill is shortened considerably, and even then it's risky.

I keep a drill index with flat bottom drills, ready to be used. I do not have a full set, but enough sizes to serve the needs.

Piloted counterbores are used, primarily, in drill press operations, where one has no control over cutting issues. They permit operations that would, otherwise, not be possible. It's quite common to spot face castings, for example.

It would make no sense for the home shop to own counterbores. They are complete only when a pilot is fitted, and the pilot is size specific. You could own thousands of dollars worth of counterbores and still not have what might be needed. By using flat bottom drills, pretty much any size can be addressed without expending a huge amount of money, and they don't require pilots (although that isn't beyond possibility, either, assuming one has a tool & cutter grinder at their disposal).

Harold

[JackF]

Harold,

Thanks for expanding even more on the counter bore subject.

Pat, sorry for the hijack, back to the business at hand.

Jack

[Patio]

Jack; no problem with hijacking, here. I learn something from all the discussions too.

Progress from the last two nights.

I don't have any counter boring bits, but I do own a little boring head. So that is what I ended up using to counter bore the holes. I took a while to get all three done, as I was only taking .025" each pass, with a the slowest feed, that I believe is .0015" per revolution.

I also was able to get the new backing plate turned tonight. Against better advise, I used a C6, brazed carbide, cutter in the lathe. I tried a piece of HSS and ruined it right away. I had gotten away with using carbide when turning my first back plate for the 4 jaw, so what the heck, I gave it another go. Harold did offer my a C2 cutter, if I needed it. Things worked out well enough.
Thanks anyway Harold!

Here are the pictures.

I am not sure that the soft jaws I am making are going to work, because of the location, the existing holes in the plate, ended up in the jaws. If not, I do know how to make another set.

Next thing is to drill and counter bore the holes in the backing plate, to mount the chuck. Hmmm, might have to try the rotary table. That will be another first. I am not sure how well it will work, It has had a hard life, and was well rusted when I got it. I think it may have been, more for wood working or for, drill press work. Nothing ventured, nothing gained!

Shop sure is getting messy, with all the new chips.
That's it for now, more to come!