Thread Dial Kits, any interest?

[FTF Engineering]

Walt, Thanks for sharing that great story. I bet there aren't a lot of original owners of lathes as old as yours. That's fantastic. Sounds like you've got a real beauty there!

Gary, The gear on the bottom of my prototype is simply squeezed between two nuts on a threaded section of rod. There's no keying or anything to lock it to the shaft, just the friction of the nuts. I know it's hack, but it works. After all, there really isn't any load on the dial.

I don't see anything wrong with a setscrew. I wouldn't want to drill and tap right through between the teeth, but if you've got a shoulder on the gear for it, then why not? I've started making blanks to try out my second hob and I didn't put any shoulder on them so I'll probably just do a press fit onto the thread dial shaft. Only problem with the press fit is it will make disassembly a little bit of a pain if I ever have to pull the dial apart.

-Bruce

[Greg Menke]

Must be threading dial season, I'm doing mine;

here's the hob, 4140 acme stock, I milled out the slots but did not put in relief;



Putting in the gashes;




Ready to form the gear;




I'd have run the job but some other projects got in the way, I should be giving it a try in the next few days.

Regards,

Greg

[RocketSled]

Ironically on ebay a short time ago I sold an SB 13 and sold our moderator Paula the SB 9A she had the long thread on.

aaaah ha! Clues to the puzzle! (What a cool group of people I've run into here. )

[garyphansen]

Greg: Are you making a thread dial gear for a 14 or 16 inch South Bend? Gary P. Hansen

[Greg Menke]

Gary, its not for a SB but the problem is so similar I figured its more or less on topic. The leadscrew is a 1 1/4 - 4, the gear is 16 tooth. I have to fit the gear with a taper pin- I wish it was held by opposing nuts or a setscrew. The measurement issue thats making me pause is how deep to make the teeth, no doubt theres lots of room for engagement but I need practice doing stuff as right as I can. The lathe is busy doing acme threading at the moment, I'll try to get some kind of center distance when I either get the threads done properly or scrap the part- whichever comes first..

My lathe is a 12" ATW, the old gear was severely worn because thread dial shaft was never lubricated, so became extremely stiff.

Regards,

Greg

[FTF Engineering]

Cool stuff Greg! You got that close to actually using the hob but you wanted to tease us and make us wait???

Did you cut those acme threads or buy threaded 4140 stock. Those threads look great! You've got what, five flutes? And what flute width did you use?

If your tread dial mounting scheme is similar to the way SB did it, then the tooth depth really isn't a critical dimension. Since you can position the dial as tight to the leadscrew as necessary, pretty much any depth will work from this:


to this:


Obviously YMMV if your mounting scheme is different, but thankfully for me, this is one dimension that I should be able to hit. [img]smile.gif[/img]

Definitely thread dial season! -Bruce

[Greg Menke]

Lol- I'm waiting too. I recently acquired a Nichols horizontal mill (for free.. [img]smile.gif[/img] ) and am working on it as we speak, which is why the threading dial is paused... I bought a length of acme stock for the hob, it was fun turning down the shank & cutting the grooves- pretty hard stuff but it made nice chips. I put in 5 flutes- which was easy since I used a dividing head on the Bridgeport. I forget the cutter diam I used, its almost but not quite too wide for the gear, lucked out on that one.

The lathe's thread dial does mount differently than a SB's. You can see the spot on this pic, sorry I don't have a closeup handy;


the body of the thread dial assy mates to the side of the apron in the obvious spot w/ 2 screws & 2 pins- it doesn't pivot. Part of the assy is a shank containing the thread dial w/ shaft & gear. The gear is engaged by sliding the shank upwards in the assy which moves the gear up into engagement w/ the leadscrew, a detent w/ spring loaded shaft locking it there. It doesn't pivot in like a SB- which is why I think I need to be a little careful with the thread depth. The advantages to such a complicated setup that I can imagine is that its easy to disengage the dial and it won't inadvertently slip back in, and when out of engagement, the top of the dial is well down below the top of the apron- hopefully out of harm's way.

The old gear is so worn that its hard to be certain of dimensions- or in fact how well it fit in the first place. It looks sort of like it was a pretty loose fit...


I'm hoping that when I get a sense of the dims I'll find they set it up for something close to standard clearance.

Regards,

Greg

[FTF Engineering]

Hi Greg,

Yeah, If I understood the engagement scheme correctly, it sounds like you've got less wiggle room on the tooth dimensions than Gary and I have.

I was asking about your flute width because that's what determines your front angle of attack. I think I had too much front rake on my first hob and I changed the flute width accordingly on the second one. Actually, if you're making your blank out of brass, then you could have milled the flute off axis to end up with a zero front rake, right?

C'mon man. Give that thang a try!! LOL!

I've got a couple of gear blanks all made up ready to be gashed but the Bridgeport is in unheated space and I just can't bring myself to go out there and freeze my fingers off to do the gashing deed. I've been trying to come up with a way to do it in the lathe without a milling attachment. Since the gashing isn't a real precision operation, I was thinking I may just eyeball it, but until I get brave enough to try that, I'm just waiting for a warm snap.

Gary, how about yours? Did you get your $12 grinder issues resolved and are you ready to make chips??

And Gary... Thank you for starting this thread in the first place!!

-Bruce

[garyphansen]

I have three of the four flutes I am grinding started, but I have been side tracked for awhile with work and needing to do my income taxes by next Monday so my kids can fill out and file their Fasa college forms by the first of March. I have bought the brass bars for the gears and Alum. bars for the dials. I am planning on making the dials 1.5 inches in Diameter. They are a lot easyer to see and read that way. I am not sure why South Bend made their dials so small. Hopefully, next week I can spend some time on this. I still need to order a 2" dia. X 1/16" slitting saw. I have a three inch dia. one but it will not work for what I am planning. I am going to make up to 24 kits (If I do not make some scrap) I hope that is enough or not too many! I think about 13-14 people has expressed an interest in one. Gary P. Hansen

[Greg Menke]

FTF- I think you're right- theres a lot of front rake on this one, mostly out at the tips of the "teeth". They aren't as deep as they should be either, not far enough below the root. The minimum order for the stock was 12", so I have enough for a few more tries if this one doesn't work out.

I haven't yet mentioned my first try where I spaced out and put in gashes for 14 teeth instead of 16, the hob cut well but of course the teeth didn't line up so the hob progressively ate the teeth off the blank. I realized what was happening but let it run to watch it cut. The blanks are 360 brass, would be better to use 660 but I figure this is a low friction application so either would be fine.

But back to the rake- I fed in small bites, allowing the hob to clear the material before feeding in more. I didn't note any tendency to hog- so perhaps the too-aggressive front rake isn't a big problem in this case. It also may be that my wide flutes somewhat mitigated the lack of top relief. If I make another hob, I think I'll try to mill some top relief by nodding the Bpt head.


Greg

[ChrisK]

Gary,
I don't know if you already ordered the slitting saw blades you were looking for but think I have some 1-1/2 and 2-1/2 dia collecting dust. I would donate them towards the project if you are interrested.

Chris

[garyphansen]

Chris: That would be Great! Do you want me to send you some money for shipping? My address is Gary P. Hansen, 6782 E. Fouch Road, Traverse City, Michigan 49684 Thank you, Gary P. Hansen

[ChrisK]

That's OK. They are thin enough to fit into an envelope. I'll send them tomorrow.

Chris

[paco]

This guy is making some excellent replicas for $100 buck (no affiliation)

http://tools4cheap.net/proddetail.php?prod=threaddial

[garyphansen]

Well I have made some progress on the thread dial project, sort of. I planned to be farther along with this project by now but outer things kept getting in the way. My wife's uncle went missing about two weeks ago. He was in the early stages of alzheimers and they had taken is drivers licence away, but he got in his car and became lost anyway. There had been reports that he had been sighted in a number of different areas of the state. The last reported area he had been in was near Grand Rapids, (about 100 miles away from his home) where he asked for directions. He took a wrong turn and went down a seldom used road until he came to a place where there was a bridge out. When he tried to turn around he became stuck in the snow. He most likely sat in his car until he ran out of gas. Then he walked to a house which proved to be abandoned. He was found face down in the snow frozen solid. His younger brother is a retired pastor and at the furnural he said "Art over and over agin keep trying to find his way home, and then finally he did."

Well, the progress I have to report is the hobb I made works but not quite like I had intended. I tested it out on a brass gear blank that had the teeth milled out. I have not hardened the hobb yet and figured that could wait until I tested it to see if it would work. It cut the invoult shape on the gear teeth find but I had not cut the flutes in the hobb deeper than the root of the tooth so it will not cut a concave shape into the blank. However, maybe I should leave it like that, what does everyone think? South Bend cut the teeth in their thread dial gear straight or angled to matched the lead screw, I guess depending when they were made. A straight gear will work, a angled gear works better and a angled and hopped gear runs smother yet. On a heavy duty lathe with massive drive gears a hobbed gear might be overkill. On a light duty lathe like a 10K or a 9N a hobbed thread dial gear would make cutting fewer than 8TPI easier. So what do you think, should I harden my hobb the way it is, or should I cut the flutes deeper to produce a concaved, hobbed thread dial gear? Gary P. Hansen

[ 02-19-2007, 10:47 AM: Message edited by: garyphansen ]

[FTF Engineering]

Gary,

Glad to hear that the hob worked. That's great news.

The thread dial gear should be under a very light load since the only thing it has to turn is the shaft that runs up to the dial wheel. With that in mind, I don't think the teeth have to be that deep at all. That concave shape looks nice, but you sure don't need that much engagement from a functionality standpoint. If the dial shaft is hard to turn and putting a lot of load on the gear, then you've got problems elsewhere that need to be resolved.

Have you got any pics of the finished hob and gear any maybe even hobbing in process?

I'm still trying to figure out a way to gash the teeth on my gear blank without using the mill. I took my compound off yesterday to see if I could figure out a way to attach my collet indexer onto the cross slide casting, but couldn't make it work.

Sorry to hear about your wife's Uncle. That's quite the story you got there...

-Bruce

[garyphansen]

Bruce: I will try to get some photos later. My friend has built a fixture for cutting the teeth on the gear. It replaces the compound on the lathe. There is an index wheel to get the 32 teeth spacing. The gear blank stands vertical and is attached to the index wheel by a shaft. The whole fixture is offset (like turning your compound) by about 15 degrees (if I remember right) to match the angle of the threads on the lead screw. Then the cross slide is brought forward to engage the cutter that is turning between centers on the lathe. Gary P. Hansen

[garyphansen]

Here is a photo of my still unhardened Hobb. I ended up cutting 5 unevenly spaced teeth. Although the Atlas die grinder attachment would adjust every which way it always seemed that I was at the end of the travel anytime I had it adjusted the way I needed it. I do not know why I did not realize I needed to cut the flutes deeper than the root of the thread so it could cut a concave surface in the gear.
What is anyone thoughts on if I should harden the hobb or not? It is made out of tool steel which in its unhardened state is much harder than brass. I have about four inches of cutting surface on the hobb and will only be using 1/2" at a time. If it becoumes dull the full lenght I can always resharpen it.
The brass gear was an extra made when I first made a threading dial a while back. I do not know if you will be able to see the involute shape of the teeth the hobb made in the photo. I have not started making the gears for the kit project yet. In hobbing the gear I have raised some burs. should I wire brush it to remove the burs or just let the burs ware off from use? The hobbed gear travels up and down the lead screw much smoother than before it was hobbed. Gary P. Hansen

[FTF Engineering]

Nice picture Gary. Thanks for posting that.

Now that's the simple solution to wide flutes... Use a wide gear! Brilliant!

I can see where the hob cut into the gear and that portion looks good, but you haven't reached the depth limit on your hob yet. You're right that you won't be able to cut a concave profile, but you aren't even at the full cut on the teeth as it is. Did you think you were bottoming out?

As for the hardening question, I defer to the experts. My only advice is to ask yourself "How much time do you have invested in it so far?" and decide how soon you want to go through that again.

-Bruce

[garyphansen]

Bruce: Have you tested your hobb yet? If so how about some photos? Gary P. Hansen