Faceplate Adventure or Sleeve Inception

[cjtoombs]

I wanted a faceplate with more capacity than the 8" one that I have for my Craftsman 12" commercial lathe. I have some castings that I need to bore and would like to do it on the lathe so I can use a fairly robust boring bar, instead of the 1/2" I'm limmited to on the mill. So I turned to my old friend eBay. I found a really robust looking one there with the correct 1 1/2-8 thread. Made an offer and a few days later it showed up at my house. Except that it didn't have the requisite 1 1/2-8 thread, it had something more like 1 11/16-8, the thread measured 1 1/2" on the minor diameter. I decided to go on and keep it, as I liked it and sending it back would be a pain. I decided to purchase a cheap chuck backplate with the correct thread and bore and sleeve the faceplate to the correct thread for the lathe.



One common problem I've found with these low cost import back plates is that the reference surface (the unthreaded portion where it goes onto the unthreaded portion of the lathe spindle nose) is always oversize. This should be a very close fit on the spindle nose to ensure reapeatable installation. I've fixed this problem before as well, which requires sleeving the backplate. Were getting to sleeving inception here, I think. First thing is to bore a recess for the sleeve, and locktite in the pipe that I use for sleeving my backplates.

Next I part off the pipe. I had to put it in quite deep as the register area on this backplate was quite deep.

This was then bored to 1.500 (the register nose is 1.499) and then faced off so that the register portion was 3/16 (the register on the lathe is 1/8" long.

After that there was a whole lot of butchery until I got to what is pictured below. I did all the final cutting with the backplate screwed to the spindle nose.
Dimensions in this picture were 2.250" diameter and 1.167" long. I later decided to cut the diameter down to 2.125 to give a little more meat on the faceplate.

With that out of the way, it was time to tackle the faceplate boring. This was set up in the mill and the existing threads bored out.

Then I bored the recess for the sleeve 1.135 deep and a close slip fit for the sleeve, which was then locktited in place.

Once in the sleeve was faced with a light cut off the entire face


I then drilled 3 holes tapping size for 1/4-28 (the only reason I used these is because I have a lot of them). These were then locktited into the holes and cut off with a hacksaw and another light cut off the entire face, then a bit of deburing with a file and it was ready to mount on the lathe.

I took a facing cut on the lathe. I was a bit disappointed that the face was out as far as it was, as I had taken great pains to clean and debur the mill table, 123 blocks and the faceplate, but I did wind up having to take about .025 or so off the face before it cleaned up.



I noticed after completing the facing that there were some cracks. I'll have to be ginger with my clamping around these, but the faceplate should do what I want it to.

 

[Larry$]

Not that you are likely to spin that face plate fast but cracks in cast iron tend to keep moving. Try some of the crack checking die so see how far the cracks go. Maybe try drilling stop holes or better have it brazed by someone with a furnace or DIY if you have a large heat source.

 

[benmychree]

For my 9" Monarch lathe, which has a spindle 1-3/4 - 8, I just made a pattern and had one cast out of cast iron, ezzy peezy.

 

[Larry$]

John York, That was a good idea. I wonder how many iron foundries would do that. Could you tell us what it cost. There have been things I would like to have cast in iron. I cast in aluminum, zinc, and other low melting, metals but my furnace won't get hot enough for iron.

 

[benmychree]

The foundry that I have dealt with since the 1960s has gotten too expensive for me lately, charging a minimum of $250 for any two part mold, but in the case of the faceplate, driving plate, steady rest, and follow rest that I made for the Monarch lathe, along with some heavy castings for a clutch mechanism and bearing caps for a good sized steam donkey at the steam sawmill that I volunteer at, they sort of shifted some of the burden to that job, and charged me $75 for the four castings; this did tickle my conscience a bit, but since I made the patterns for all the parts and machined them for free and did the babbiting for free, I did get over it. Since then I have found a new foundry that will work cheap for cash ---, I can send them a pattern in the mail, they pour it, send me the casting, and I slip some cash in the mail. If you would like to know contact info, PM me.

 

[benmychree]

I used to do a lot of foundry work in aluminum, brass and bronze at home, finally gave it all to a friend who combined it with another lot that he got from a school hereabouts; he has yet to use any of it, but he is a class 10 firearms dealer (anything short of nuclear weapons) and has plans to make some parts for artillery sights, he has over 40 artillery pieces from about 20 mm to 75 mm including a Bofors antiaircraft gun, what we kids used to cal an ack ack gun. Most of the foundry work I did at home was bronze parts for the marine steam compound engine that I built and sold casting kits for, I sold the whole project, so I no longer needed the foundry, and it took up space needed for other pursuits.

 

[cjtoombs]

Not that you are likely to spin that face plate fast but cracks in cast iron tend to keep moving. Try some of the crack checking die so see how far the cracks go. Maybe try drilling stop holes or better have it brazed by someone with a furnace or DIY if you have a large heat source.

They are pretty close to all the way through at this point. I will just avoid clamping in that area, and if I forget, well, I won't clamp there anymore after that. As for brazing, I think there is way too much oil in there to get a good joint without breaking them out and cleaning the area before trying to braze them back in. I think it will do all I want it to without worrying about repairing it. As a side note, it has 24 holes around the back face, so I wonder if it started life at some point as a rotary table, the pattern of the T slots is reminiscent of a rotary table.

 

[Larry$]

To braze a casting you have to V out (with a grinder or end mill) all of the crack. Then fill with the bronze filler rod. Your flux will float impurities to the surface.

 

[cjtoombs]

So now we get to the reason I wanted this anyway, and of course I had to make another tool. As an aside, I ordered a set of 5C collet blocks to make a boring bar to use with this, and then I had to make a spanner wrench for the collet block nuts. So I basically built a tool, to build a tool, to build a tool. Anyway, back to the story at hand. I needed to bore a casting, so I was going to need an angle plate. I wanted one that would be versatile and work on this faceplate for this and future work as well. I have some 4" x 3/8" angle, so that's what I based it on. Did a model in Fusion 360 (I almost always do, as I use a CNC mill for a lot of this work, and need the model for generating the G code). So here's what I wanted it to look like. Well, maybe not that shiny, but you get the picture.



The keys are held on by #10 socket head cap screws countersunk into the keys. The center hole is for a 3/8 bolt. The 15 holes in the face will be tapped 3/8-16, but I didn't bother to model that. I roughed it in by milling the faces and edges of the angles. The face was off square about .020, I knew these structural shapes were not precision, but I was expecting a bit better than .020 at 4".



Tapping 15 holes straight required a guide, I used a piece of scrap from the scrap bin and drilled a hole.



I had some trouble with the 10-24 holes for the keys. I think my taps were either not heat treated properly or the flutes were too thin, because they would break off little pieces of the flute. I was able to wiggle them around and get them out, broke the remaining two like that from a three tap set, then found another of a different brand that worked fine. I used the CNC to rough the curve on the angle plate out, but I don't have any pictures of that. I left about .050 on it, and roughed out the keys and t nuts on the bandsaw. I then clamped it to the angle plate and used a Rube Goldberg setup with a boring bar to finish it in situ. The long limber setup chattered like nobodies business and I could only take a max .010 cut at a time, but it got it good enough.



That's an MT3 quick change toolholder turned upside down and using an adjustable parallel to set the height. I then debured it and treated it to a good cleanup and cold blueing.

 

[cjtoombs]

So here's the part I'm machiining on it, part of a casting kit you can find here: https://mlatoolbox.com/MLA-18.html. I had a long explanation about this but my computer hickuped and I don't feel like typing it in again. The gist is that I screwed up the start of machining of this part and this faceplate/angleplate combo is to do this right and correct that error. Anyway, here it is.




If you look closely you will see that that center hole is not in the center. I later plunged an 11/16 end mill into it until I cut out the bad center and then put in a new one. It will be drilled and either reamed or bored to 7/8", so the 11/16 hole will disapear. I also machined the edge so that I could grab it in the chuck for the drilling/boring operation.