Bores in a Line! -- Lineboring on a Manual Lathe

[The Metal Butcher]

Tada!

My project that was designed up 9 months ago is finally complete. Or at least 1 part is, the other slated for tomorrow.



So if you've seen any of my past 4 threads related to this topic (1, 2, 3, 4), then you are familiar with the part in question. In thread #1, I asked and received some great advice on how to do it. What I ended up doing was almost exactly what mattthemuppet said in post #2:

I'd knock out most of the hole on your camelback with a big azz drill. Then I'd cobble together a fixture plate for the [Lagun] that I can bolt to the carriage somehow ( make a dovetail like clamp and attach it to the cross slide dovetail with the cross slide removed, through bolt it to a plate under the carriage, something like that) and then bolt the whatsit to that. Make a long single cutter boring bar to hold between centers, stick a cutter in it that can be adjusted with a screw at the end and then line bore it.

Seems simple from this chair

Simple from this chair too. Just time consuming.

So here was my process. Like I said in the other thread, I did make centers on both ends in the Bport (Well I did one, my helper did 3 ).




First I edgefound the sides of both tubes. Then I edge found the top and bottom of one tube, then switched coordinates on the DRO and did the other. Then I averaged the two values to find the best approximation of center for the weldment. My longest twist drill was just short of being able to all 4 bores, so my "center" for the other side was just a hole cut with an annular cutter. I am glad I did not try to bore these in the Bport. They are not rigid and wiggled badly center-drilling. Surprisingly there was no wiggle with the annular cutter.

Dad did me an incredibly great favor by figuring out a fixture plate for the lathe. We had these strange clamp blocks that griped a dovetail we got in an auction. Maybe for a smaller lathe? Dad modified them and made them longer with a spacer. Then he added some holes to the side of our Tom Lipton style mini-pallet. This made for an excellent and strong clamping setup.







(The feeler gauge was to take up rock from the weldment.)

Con't....

[The Metal Butcher]

To mount the weldment was quite easy. I just mounted the part between centers, and drew up the plate tight, then tightened the plate clamping screws. That's it.







After that I drilled it with a 1 3/8" twist drill in the headstock, feeding with the carriage. Then I switched over to my boring bar. My first cut went from the drill size to 1 5/8" with no issues. Even curled off a nice chip from time to time.

My friend took some video. See here:

It's a little squeaky. Turn your volume down.

I did start to get some chatter for my finish passes. I was able to remove it by way upping the feed rate, but I didn't really want that for my finish passes. However, all worked out well and I got just the bearing fit I wanted. If could have been a tenth or two tighter, but I did want them to be a slip fit. As you can see in the end of the video, they slide in so long as they are perfectly straight. All 4 bores came out perfectly identical, to no suprise.

For measuring, I asked for advice. tom_d recommend

Knowing the diameter of the bar all you need is a small hole gauge to determine the gap between the bar and hole. Make several measurements and take an average if the bar is not running concentric. Gap x 2 + bar dia. = hole dia. Note: gap should equal the cutting tool projection from the bar.

Which worked ok. Unfortunately the bar was so limber that one could actually deflect it a few tenths just tightening up the small hole gauge. Any error was of course multiplied by two, making it challenging for a snug fit. But of course this was a waste of time really. As the bar is a MT4, I could just remove the tailstock center and roll the carriage out the the way. With a 24" bar on a 40" C-C, I could measure any bore with standard telescoping gauges.



I do now mark my centers with sharpie in case there is any small amount of runout. That way it is certain to be returned to the same position.

[The Metal Butcher]

So yeah. It turned out nice.

I did end up spotfacing all shoulders and chamfering. The spot facing worked great, the chamfer was chatter prone. I've learned that so long as your cutting forces are in line with the bar, you can do what you want. But angled cuts cause bad chatter. Hmm. Kinda like what the machinery's handbook was trying to tell me. :P









My cutting tools were all ordinary. A RH turning bit, a grooving bit, and a chamfer bit. Only difference was they were 3/8" round and cut down to be 3/16" at the cutting edge. I forgot to get photos, so use your imagination.

For those wondering about the part, it is a part of a NASA HERC rover. Part of my senior design project. Though I've graduated, I'm still helping make some progress as it is fun. Lastly, the axles will be cut short. They are going to half shafts, so don't worry about any load.

You're about to do a setup where the lathe becomes the functional equivalent of a horizontal boring mill. I'm not sure how many people who participate here have ever done such a thing, so I would like to ask if you could post some pictures of the setup once you're up and running. I think it would be an excellent viewing/learning/teaching experience for many. The ability to share this type of knowledge is what helps make this site so great.

So Tom, hopefully that is enough detail to satisfy? It certainly was a fun experience! I hope more folks give it a try. It's a great way to get more out of an existing tool that is very hard to replicate on most other home shop machines. I think Nickle City has been doing a great job lately of showing why the lathe is the best tool ever. When I get my big Daewoo up and running, I intend to make mounts for the saddle so I can do long and big bores. It would be the perfect machine for it.

[tom_d]

Simple from this chair too. Just time consuming.

No. That's not time consuming. That's all time well spent. You've done an excellent job doing a complex project using simple machines combined with refined skills and talent. And that time was skewed a bit. Bent, if you will, in the shape of a curve. We call it a learning curve. Congratulations on a job well done, and thank you for sharing your learning experience with us.

[Paul Alciatore]

Line boring in the lathe: welcome to the club. Looks like you did a fine job. If your ways are straight this technique ensures almost perfect alignment of your holes.

You say your assembly is "...part of a NASA HERC rover." I see that the 2021 winners have been announced. Did yours win?

Here are some photos of how I did it to make a better part for my Unimat. The original CI part developed a crack so I made one from a block of aluminum that was both stronger and also more versatile with multiple mounting positions for the Unimat headstock. The hole being bored is to fit on the vertical column and it needed to be parallel to three of the faces of the block. The line bore in the lathe was my solution.



The first photo is an overall shot of the process. The table it is sitting on is a milling table I made for the SB lathe. It mounts with the same mount as the compound, which is removed when it is in use. As you can see, I use clamps from a standard 3/8" clamping set to secure parts to this milling table and I have an assortment of shims (shim stock and flat ground stock) to elevate it to the proper distance above the milling table.



This next photo shows a rough check of the diameter of the bore. My boring bar was not ground to size so I turned an area on the end which is visible in the first photo. Here I am checking the diameter using a drill bit. I did the final diameter measurements with a pair of outside bow calipers, transferring the measurement to my micrometer. And then a final check by removing the tailstock and using the Unimat vertical column, which is 25mm diameter.



My cutter is a round, HSS bit held in a hole with a set screw. The opposite side of the hole has another set screw in it to allow fine adjustments and I milled a flat, which is visible in the first photo, to make the use of a depth micrometer easier. I used a large nut with both sides ground flat and parallel as a spacer. It sat on the flat on the boring bar and the depth micrometer sat on that spacer. This made fine adjustments in the cutter's position easy and accurate.

In the end it was a perfect fit and parallel to the three sides to my ability to check it.

In case you are wondering, the holes in the other end of the block are for three different positions where the Unimat's headstock can be mounted when this block is used.

[olf20]

Thanks for sharing! I've learned so much from all of the post on this forum.
As I'm 74 I guess I'll die a rookie, not enough time to learn all the tricks. LOL
olf20 / Bob

[nickel-city-fab]

Oooo nice job! I like that setup with the tooling plate.

[mattthemuppet]

that is super cool, thanks for letting us all know! Even a blind squirrel (me) finds a nut every now and then Just don't tell my wife I was right about something

[The Metal Butcher]

No. That's not time consuming. That's all time well spent. You've done an excellent job doing a complex project using simple machines combined with refined skills and talent. And that time was skewed a bit. Bent, if you will, in the shape of a curve. We call it a learning curve. Congratulations on a job well done, and thank you for sharing your learning experience with us.

I guess that is a fair assessment. Thanks for the help Tom!

Line boring in the lathe: welcome to the club. Looks like you did a fine job. If your ways are straight this technique ensures almost perfect alignment of your holes.

You say your assembly is "...part of a NASA HERC rover." I see that the 2021 winners have been announced. Did yours win?

Here are some photos of how I did it to make a better part for my Unimat. The original CI part developed a crack so I made one from a block of aluminum that was both stronger and also more versatile with multiple mounting positions for the Unimat headstock. The hole being bored is to fit on the vertical column and it needed to be parallel to three of the faces of the block. The line bore in the lathe was my solution.

Ways are quite good on that machine, and it was freshly leveled, so I'd say it's decent.

We did not get to enter due to not being finished. It is still being worked on. Another team at my school did enter and win third. I don't want to trash my teammates, but I will say that they started with a rover from the previous year that was about as complete at the end of the year as it was from the start. It sort of worked, but had a lot of easily fixable reliability issues and generally low quality workmanship. We did not have an actually competition this year due to covid, so rovers were judged on design and other factors. My school did take first a few years ago.

Ours, in no small part due to me, became highly complex and precise, with almost every component seeing machine work. As a result I think we have an incredibly light and strong platform. Whether our engineering choice works out is yet to be seen. But so far the components I've built appear to work very well with a few exceptions. I've been saving up a lot of content in regards to it, for when it is finished. If and when that happens, I will post some of it. I cannot claim it all as mine of course, and will give credit to my teammates where appropriate. I am proud to say though, that up to this point (if you count alumni of a few years) it has been 100% student built. Designed, welded, machined, everything.

The rover will be passed off to a new team in about 20 days here. Being highly invested in it, I want to see it through so I intend to mentor them and help them along. There is certainly plenty of engineering challenges left on it, but I have learned a great deal of experience in the last 12 months that can speed them along. Should there be a competition in 2022, I think our rover will stand a very good chance of placing first.

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Very nice work on your unimat. Your solution looks very similar to mine. I must ask though, if you were removing the tailstock to measure with twist drills, why not just roll the carriage another inch and check with calipers or telescoping gauges.

Oooo nice job! I like that setup with the tooling plate.

Thanks NCF! Thanks for being a inspiration with all your impressive lathe problem solving as well.

that is super cool, thanks for letting us all know! Even a blind squirrel (me) finds a nut every now and then Just don't tell my wife I was right about something

Thank you Matt! I'll be sure to tell your wife should I meet her.

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I finished up the second today. I was in a hurry and got a bit sloppy. Ended up with a 1.5 thou oversized fit. I'm going to blame that with not sticking to my normal triple pass strategy for finishing cuts. At any rate, nothing a bit of loctite 648 can't fix. I wrote a note on there for anyone who has to remove them in the future haha.

[Paul Alciatore]

The check with the drill bit was just a rough one and I wanted to do it as quickly as possible as I hogged out the hole to get close to the final diameter. The small size of the drill bits allowed me to just move the tailstock but did not require removing it from the lathe. My SB has a 24" bed. As I said, I did use a bow caliper and a micrometer for the final check with the tailstock removed from the ways. This took a bit longer for each measurement.

And, of course the final check with the Unimat's actual column as seen in my last photo. I did that before I took the boring bar out of my 3 jaw chuck so that the adjustment of the cutter would be retained and I could have made another finishing cut if it was needed. But my measurements were good and the Unimat column fit perfectly.

Besides, that was the first time I did this type of operation and I was feeling my way through it.

This photo shows a lot about what I was doing. It is the step before the boring done in the photos in my other post above. In it I am milling the flat on the boring bar for setting the cutter's protrusion.


The green oval shows the original Unimat bracket. If you look, you can see the crack at the threaded part of the screw hole that attaches it to the vertical column. It is not visible here but I did make a reinforcing plate to span the crack. That plate has new threads so the crack is no longer being deepened. It is holding the Unimat headstock which is doing the milling cut on the boring bar.

The red oval shows the partially complete, new replacement bracket. And the blue circle shows the drilled hole that will be bored to it's final diameter by this boring bar as seen in my previous photos.

This illustrates part of the versatility of this bracket as the flat sides are ideal for attachment to a flat surface, like the compound in the lathe. And the mounting holes at the left end in this photo allow the Unimat's vertical column to be mounted to it. So, now that it is complete, it fits both under the column as a base and on the column to hold the Unimat headstock. It is a very handy accessory to have.

Another trick that I used is visible in this photo on the right edge of the new bracket. After the in-line boring operation, that end was opened with a saw cut so it could be clamped on the column. The holes for the clamping screws are visible are visible there. Three of them are somewhat larger and have been counterbored so the SHCSs sit below the surface. The other two are smaller because they are the threaded ends of two identical screw holes that come from the other side. That way, no matter which side of the bracket is facing me, I can have the screws on that side for easy adjustments.

While this set-up is not good for making heavy milling cuts, it does allow me to easily do things like this flat and to drill the holes for the tool bit and it's associated set screws while the boring bar was in the lathe. Besides, I did not have a full sized milling machine at that time and while the work could have been done on the Unimat, it would have been even more awkward there due to the size of the boring bar. And indexing on something that size there would have been all but impossible. On the left side of this photo you can see the row of holes in the chuck's back plate and the indexing arm used with them.

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Very nice work on your unimat. Your solution looks very similar to mine. I must ask though, if you were removing the tailstock to measure with twist drills, why not just roll the carriage another inch and check with calipers or telescoping gauges.

...<snip>....