Low lead attachments

I'm starting this thread as a result of a conversation that began between me, and a couple other members about the possibility of scratch-building a few Low Lead attachments that would fit our various K&T mills,and possibly other makes as well, due to the near impossibility these days of finding suitable units in the wild. After all,if a worldwide forum full of machinists can't build a relatively simple gearbox,then I think we may be in trouble.I personally at least, am not really interested trying to do this as a "for profit" venture,as much as I am in trying to fill a need for a very hard to get,but in some cases very vital piece of tooling.

My(and hopefully our)goal would be as follows:

1.To gather together, and share as much information as possible about the specifications of various Low Lead, and for that matter Standard Lead attachments that fit Kearney & Trecker ,and Cincinnati as well as other makes of milling machines.

2. To use the information gathered to produce a set of working drawings for a Low Lead attachment (or attachments) that can be adaptable to fit at least a wide range of models of K&T mills, and hopefully,possibly other makes such as Cincinnati,as well others.

3. To make available those drawings to members of this community who wish to build an attachment such as this.

4. To actually build (hopefully as a cooperative effort with other members) a small number of these attachments, and use the economy gained in making more than one at a time, to make it a relatively affordable project.

I realize that this is no small task, and it will take a lot of help from friends that I haven't even met yet. It will also take time which seems to be in shorter supply every day at least for me. It won't be free, but hopefully we can use our cooperative knowledge, and resources to make it as inexpensive as possible. I will try to keep up with this thread and reply promptly as needed, but I am the Owner/operator of a one-man machine shop,with more projects, and broken down junk than I can keep running, so bear with me if it takes a few days to hear from me. I'm looking forward to seeing where this goes.

Correct me if I'm wrong.
A low/high lead attachment is a system to gear one of the feeds to another device.

You could add:

System of that brand for the DH on that machine

Attachment provides MULTIPLE gear ratios by means of changing out components (gears, etc - the ETC on K&T being not only gears but WORM SETS)

This is done in reference to recorded data applicable to that attachment published by the attachment manufacturer - to achieve some specific task - such as thread milling

Miguels244 said:

Correct me if I'm wrong.
A low/high lead attachment is a system to gear one of the feeds to another device.

Click to expand...

johnoder said:

You could add:

System of that brand for the DH on that machine

Attachment provides MULTIPLE gear ratios by means of changing out components (gears, etc - the ETC on K&T being not only gears but WORM SETS)

This is done in reference to recorded data applicable to that attachment published by the attachment manufacturer - to achieve some specific task - such as thread milling

Click to expand...

The simplest, cheapest way to make this happen these days is via electronic gearing.

I have both a standard and a low lead box. To duplicate the LL box, gearing, and drive shafts would be in the several thousands each in lots of a dozen. Certainly mine is available for a lot less.

As Miguels posted, electronic would be the way to go. I'd be willing to wager the same thing could be done for less than $3,000, and would include tying the motor to the table position, not the lead screw rotation. This would allow reversing the table without removing the cutter from the workpiece, and negate the effect of wear in the lead screw showing up in the lead of the workpiece. It would have the added benefit of digital display on table length position.

An additional benefit would be the application of any dividing head to any mill.

Edited post while Miguels was posting.

gbent said:

I have both a standard and a low lead box. To duplicate the LL box would be in the several thousands each in lots of a dozen. Certainly mine is available for a lot less.

As Miguels posted, electronic would be the way to go. I'd be willing to wager the same thing could be done for less than $5,000, and would include tying the motor to the table position, not the lead screw rotation. This would allow reversing the table without removing the cutter from the workpiece. It would have the added benefit of digital display on table length position.

Click to expand...

For quite a bit less the drive could be geared to the lead screw.
This is actually over powered for the purpose, but would certainly do the job.
Electronic Lead Screw Main Page

First of all, you're both right as far as electro-driving by whatever approach being the easiest/simplest way out.I even considered it myself for a while. That being said, that's not what I'm going for with this project. if it was, I'd just let my friend with a CNC shop do everything in line for me. I am approaching this from a very advanced hobby project standpoint. As I said in my original post I'm not doing this for money which means ,as far as this project is concerned at least, my time is worth very little. I can spline shafts, and I can cut gears and I'm working on a waste oil foundry to enable me to pour cast Iron in enough quantity to cast a few housings etc provided that I don't decide to fab them up from plate. I know that the worm/wormgear sets will take some doing, but aside from that, from what I've seen the rest are spur, and bevel gears,which can be which can be made plenty well for this application here at home. if not purchased as stock gears from suppliers.
What I am trying to find out is as much about the original K&T units, shaft spacings, internal gear dimensions, tooth counts, shaft sizes etc. so that I can design a unit, that will operate as the original units did, and fit as many mills as possible with minimal modification,and make a set of drawings to share here that will allow anyone as crazy as I am do try to build one too.
I DO appreciate the interest, and don't want to discourage discussion of the electro-drive approach, but I WANT GEARS.

Thanks to the nice people that have shared and uploaded their manuals to Vintage Machinery, I've been reading as much as I can for the last few days on the L/L attachment. I'm probably going to state the obvious to some people but here's what I've been able to find out. The 5814 L/L doesn't fit the smaller mills because the tables sizes are different.

The DH locating keys and PTO dimensions are different between the model "H" & "K" dividing heads.

The 5814 fits all machines starting with the 2ch, 12" table.

I'm thinking the L/L was made to fit all the machines but the DH's would have to be shimmed for the PTO height and location on the smaller mills

Some more scans.

That's great info I hadn't had a chance to go through all of it yet, but from what I read on another thread Which I believe was started by Archie Cheda, the smaller table machines also have slightly different drive shaft to lead screw spacing under the table as well. I just noticed that you already have that info here too. I'd like to think that there would be a reasonably simple way to make that adjustable, as well as the output shaft, but it may just be simpler to make two different boxes like K&T.
Thanks again for putting those up here. If we can't accomplish anything else at least maybe we will compile the definitive book on K&T Low lead attachments.

gbent, what machine does your LL fit, or which model is it?

The conventional lead covers leads from .670 to 149 inches, with power starting at 2.5 inches. I was looking at the aux. gear on my mill and it isn't tied to the spindle speeds, its a constant RPM. I'm not sure what it is but I'll find out soon enough. I'm thinking somewhere between the conventional lead, the aux output shaft, and what Mr. Beckley23 (thank you, it's a great detailed write up) did with his differential indexing attachment, we could come up with a hybrid PTO driven gear box to power a rotary table and DH for the low leads.

Here's the link to his thread and a few of his pictures. http://www.practicalmachinist.com/v...-t-model-h-dh-differential-attachment-223983/

Brianison said:

gbent, what machine does your LL fit, or which model is it?

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Its the late model 5814, styled to fit the later model machines (S series). There is an earlier model, styled similar to the H and K machines. AFAIK, the two are interchangeable.

It fits all the machines listed in Hobby Shop's attachments of the mounting dimensions table from the K & T attachments brochure.

Does anyone know whether the saddle PTO/attachment input shaft speed was the same between the H/HL series machines, and the 5184 compatible models or not? Since the 5184 box fits far more machines,it looks to be the one to copy, But since I have two model H machines I'd like to be able to adapt the inputs via a small offset gearbox or the like. As if copying a LL attachment wasn't ambitious enough.

Brianison said:

Does anyone know whether the saddle PTO/attachment input shaft speed was the same between the H/HL series machines, and the 5184 compatible models or not? Since the 5184 box fits far more machines,it looks to be the one to copy, But since I have two model H machines I'd like to be able to adapt the inputs via a small offset gearbox or the like. As if copying a LL attachment wasn't ambitious enough.

Click to expand...

Yes, Model K & H have the same lead values and use the same change gears for the leads.
I'm thinking it's not an issue if the 5814 LL will fit the H machines. It's an issue of driving the DH's without shimming the height and offsetting the keys. Take a look at the end table drawings and dimensions.

Correct me if I'm wrong, but if you look closely at the table end dimensions, both the horizontal center to center distances, as well as the vertical relationship of the PTO, and the lead screw centers are different on the H machines. They aren't big distances, but since the splined PTO shaft has to slide in the saddle with table travel, those shafts must remain parallel,and in those relationships to each other. If that's correct, then you would need some way to take care of the mis-alignments of those shafts to their corresponding gearbox couplings

If you look at the model 2H end table dimensions, they're the same as the 2CH. 5814 L/L starts with model 2CH. They had to use an eccentric bushing or a pivoting bracket to make up the variations between the table ends. It's the non standard PTO heights and side to side dimensions that make the 5814 not recommend for the smaller machines.

I found this thread today while looking for info on the LL. I think it confirms my suspicions that 5814 will fit the smaller mills, Only with a sub-plate.
http://www.practicalmachinist.com/v...-iron/helical-lead-30t-drive-gear-k-t-160142/

Aha,you're exactly right! I didn't catch that. I had never seen any reference to the means to fit it to the smaller table machines, so I had always assumed that they were non-compatible due to that. Thanks for pointing that out to me. To my mind, that was going to be the biggest bugaboo in making a "one size fits all" outfit. As far as the output side is concerned, as you said, shimming, or offsetting the D.H. or rotab, would be a relatively minor obstacle,at least in my opinion. I know that some folks have talked of using universal joints to allow mis-alignment of the device they were driving. I'll try to locate that thread and add a link here.As long as the U-joints are timed properly to each other, and the shafts are parallel, they should not cause error.
The only other issue would be the relation of the stop rods to the smaller table machines, but that could be taken care of with some offset couplers if anyone really needed stop rods.

My next question is: Is the gear ratio 1:1 between the input on the box, and the the shaft coming out that drives the change gear train ( hand crank shaft on the diagram) or is there a reduction there somewhere. Gbent, or one of the other LL owners might be able to tell us that.

The low lead box on my 2hl has a provision for adjusting the output shaft to fit various attachments such as rotab, dividing head.. The bearing bracket which supports the output splined shaft is slotted to provide slight adjustment...

The table mounting however is another thing.. Also, the auxiliary shaft used on the low lead box has to be in alignment with the box and the drive gear underneath the table.. Ramsay 1

Ramsay, do you happen to know which model Low Lead box you have? That feature definitely would solve a lot of problems up top.
I wonder what K&T used to allow mounting the 5814 box to the 2CH, because it has a different aux. shaft/table screw spacing than any of the other mills that box would fit. At least according to the sales literature, they claimed it would fit the 2CH. Anybody?