Boring Advice Sought

[jorogi]

Tools at hand,
Gorton knee mill,
News rotary table,
Narex boring head,
Accurite DRO,
new end mill.
All of it is in good shape.

Job,
Block of 1 1/2" steel needs a clearance through hole, with a counter bore on either side for bearings to press in and run concentric with each other.

Granted the weak link is me but the question is how would you do it. Bore the counter bores with the Narex, or cut them on the rotary table, and why ?

 

[Tom Kitta]

If you have a lathe - use that.

If you do not have a lathe use a milling machine with a boring head.

Drill hole to close to required dimensions.

Bore the hole out very slowly if you do not have reamers.

You need some kind of boring bar that your boring head takes.

You don't need to cut to dimension on both sides - you can just bore to size in one go and then keep bearings apart with a pipe. If that is not possible you will need to make sure you place your work exactly in the same spot - this may be tricky depending on how concentric you want things to be.

If bearings move with a lot of force or crunchy you made the hole too small. Lathe comes handy with emery cloth here.

 

[PeterT]

Based on what you've described, a lathe setup is probably more efficient as long as you can hold it & register the part reliably. Boring heads are good at what they do, but it takes a lot of cycle time to increment, bore, repeat.

Left, you can do 4 features in one setup: face + clearance hole + bearing OD & c/bore depth (orange = 4J chuck jaws for ex)

Right, flip the part & essentially repeat. You can maybe even utilize your prior bearing dial settings if bar remained in position. The trick is registering the 2nd bearing hole to the first concentric & parallel. Ideally you want to reach in there with DTI to set concentricity. If that's not practical, think about what is is most accurate. The clearance hole is probably less reliable if you just hogged it, but if you skim bored that too in step-1 it would be better. Maybe a dummy shaft temporarily landed in the bearing to indicate off? Also consider backstopping the part on the rear face which is machined face vs just counting on the jaws. Good luck!

 

[jorogi]

Holy cow, a month since I asked the question, obviously I need a chat with SWMBO about workshop time allocation.
So I finally finished the "block" and feel I should post up some pictures etc, it's nothing exciting but it should prove to be occasionally useful.
It ended up as two "blocks" (only 2). Unfortunately I forgot to take a picture of the starting point with the first block. It was the ugliest piece of steel I have ever played with, totally covered in snot gobs of weld, each gob different than all the others and all completely random. I can't for the life of me figure out how it got that way. Now Peter and Tom gave very good answers to my query and I should use my lathe more for other than round stuff, but I didn't want to use my lathe for two reasons. First, the hole in the block was to be far off center and balance and workholding would have to be dealt with and I didn't want to do that on my 9 inch South Bend. Secondly I wanted to use both my rotary table and my Narex boring head as I wanted to increase my experience with these two tools.

This is the first block, it's odd shape was simply the result of its original shape. The counter bore for the bearing was a little bit closer to the edge than I wanted but still workable but the opposite counter bore was way out of line. Not sure how I pooched it so bad and frankly I was too PO'd to care although I should have taken the time to figure it out. The hole was not on center side to side but I don't think that was it, probably some silly arithmetic error. Anyway, roughed out on the roatary table and finished with the boring head.
Block two started life as one of a single post car hoists arms.

Here it is after some bandsaw love. This one was also roughed on the rotary table, outer shape, counter bores, center clearance hole and chamfers. I finish bored with the Narex as well as facing the bottom of the bores. That went really well and was a lot easier than I was anticipating. So a bunch of work with the files and emery, turning a shaft, a finger brake wheel and a couple of glorified washers. Both bearings and the shaft were nice light press fits, runs smooth. So here we are.

A simple block to hold a grinding wheel on my mag chuck to dress a diamond wheel on the surface grinder.
Time invested, way too much. Fun had, way too much. I learnt some. I do wish though that I had drawn it up first and then made as spec'd rather than winging it.

 

[kstrauss]

I'm a little late to the question but... I would definitely follow Tom's suggestion of boring all the way through the stock and adding a "pipe" spacer. That avoids all of the time consumed and possible errors of flipping and re-centering. The pipe diameter is not especially critical and you can always secure with a few drops of retaining compound. Why make life difficult without any obvious benefit?

 

[jorogi]

I'm a little late to the question but... I would definitely follow Tom's suggestion of boring all the way through the stock and adding a "pipe" spacer. That avoids all of the time consumed and possible errors of flipping and re-centering. The pipe diameter is not especially critical and you can always secure with a few drops of retaining compound. Why make life difficult without any obvious benefit?

Learning, that's all. Getting fits right on unimportant parts makes success on important bits later, more likely. One of the bigger time wastes was getting the chamfers right, totally unnecessary but I managed it and upped my skill set somewhat.

 

[kstrauss]

Stefan's latest video is a great explanation of how to centre things on the mill. See

 

[jorogi]

Stefan's latest video is a great explanation of how to centre things on the mill. See

Haven't got to that one yet and ToT just posted TWO ! WOO HOO !

 

[ShawnR]

Just for the sake of setup discussion.....

Do not know if it would have worked, but I might have attempted it this way. Would this work?

Drill/bore the through hole first using a four jaw on the lathe, then with a rod that just fits, put that in the tail stock chuck and verify it goes through the work piece as an alignment jig. Then bore the bearing recess. Relative to the workpiece surfaces, remove and reclamp the workpiece with the opposite side out and use the alignment rod to ensure the piece is in the same spot. Then Adjust as required and bore the second bearing recess. Instead of a 4 jaw, I suppose a face plate would work, but the realignment after removing it might be a little more difficult. Don't know. I have not used one much.

You are right @jorogi , interesting and fun project. Good for you for getting it done!

 

[Susquatch]

@jorogi

I like @ShawnR's idea of using an alignment rod. But FWIW, I prolly wouldn't try to flip it for the other bearing recess. Instead, I'd bore just one hole on the lathe or the mill, and then make a center bushing to seat the two bearings on. Depending on your seating needs, it could be a floating bushing or a press fit or pinned in place with a drilled through pin. The advantage of this approach is one setup and perfect alignment.

 

[kstrauss]

As I suggested earlier: quicker and no accuracy issues.

 

[Susquatch]

As I suggested earlier: quicker and no accuracy issues.

Sorry, didn't see your earlier post. That makes two of us!

And now that I have read the earlier posts, I see @Tom Kitta had a similar suggestion too.

 

[jorogi]

Alright, respectfully you're all fired.

Here at Johnny's Blocks, we hire the best and brightest young minds and pay them accordingly.

Re post # 1, the tools available to the machining department has been detailed as has the design parameters required. As per our inclusive team centered approach here at Johnnys, the expert opinion of the machining cohort was sought to establish the best method for the manufacture of the design of the he part. Work flow, tool holding, order of operations, potential unseen problems etc.

Management initially consulted with marketing and established the vision, design was then read in and their proposal sent to engineering. Now to production, but unfortunately the ball has been dropped. With the new world economic climate, the board will not see clear to a retooling of their production facilities nor do they want to sub out production to some lah dee dah operation with lathe facilities. Further, with the thousands already invested in marketing research, r and d, engineering, health and safety consultations, enviroment, there is no appetite to redesign the new Johnny Block, so the machinists can have it easier.
So please in the interest of retaining your employment please reconsider the ask in post # 1 and kindly stay within the confines of the parameters as set out.

 

[Susquatch]

Anybody ever tell you that you have a stubborn streak?

So please in the interest of retaining your employment please reconsider the ask in post # 1 and kindly stay within the confines of the parameters as set out.

Yup, just like every other great corporation, Johnny Blocks has been hog tied by the finance department and will surely fail.....

Management is too stubborn and has no clue about the reason why we have lathes.

But as per the request from the sales department.

Work flow, tool holding, order of operations, potential unseen problems etc.

Tools at hand,
Gorton knee mill,
News rotary table,
Narex boring head,
Accurite DRO,
new end mill.
All of it is in good shape.

Tooling assessment by machining department.

We can do it, but we need a raise. And somebody please fire the finance department and send management to a conference on proper management of skilled staff.

Job - Block of 1 1/2" steel needs a clearance through hole, with a counter bore on either side for bearings to press in and run concentric with each other.

Use some crap steel to make a vise stop since its not on your tooling list.

Write a work order to have the mill trammed by competent maintenance staff.

Have a few cups of Joe, ask your team how they enjoyed their weekend off, and then get to work! Gotta be done before management returns.

True the block, and make registration surfaces on the block so it can be flipped and maintain alignment. If you don't do this,

The opposite counter bore was way out of line.

Zero the X & Y coordinates on your DRO at the registration surfaces.

Move the X&Y axis to the desired hole location and record or save the offsets.

Make sure you include enough clearance for the hole web.

Drill the through hole.

Use the Narex Boring head to bore the top side bearing recess.

Flip the block against the registers.

Touch off the X coordinate register and rezero.

Move the x axis to the previous offset and then bore the opposite side bearing recess.

Alternative Assessments.

Rotary table - too much fiddling to clamp parts, find center, create registration surfaces, and clamp adequately. Probably a good time to oil it though......

Lathe - a total waste of money sitting there unused when it would have been sooooo easy to make a bushing. I'd ask the accounting and assets department to sell it or at least hire somebody who knows how to make bushings.

Hopefully management has returned home with a new appreciation for the guys who do all the work that they can't do. And don't eat at the joint where the finance guys are flipping burgers now.

Round of applause for the machining department please!