Restoration/Repairs on a 10" LD Utilathe - Standard Modern

[Brent H]

Yes @YYCHobbyMachinist it was a chuck spin from some past life. It is bearing bronze, should have made a nice insert to replace the saddle threads in the Cincinnati tool grinder as those were chewed up and cast iron.

it does have a tendency to spin as @eotrfish mentioned unless squished tightly- you can see the dimples from some other chuck it was in before. It was a piece off the end of a much longer tube that was just long enough for the job. It would have been machined down to OD on a mandrel had the threading worked out. Alas...

 

[Kelly McLaughlin]

Hi Brent! I'd rethink that order of operations. better to have equal pressure and good grip than unnecessary strain on the chuck when you're internal threading or any operation really. ; )

 

[Dabbler]

Sorry about your gear, @Brent H - I hope the repair+cost isn't too painful!

 

[Brent H]

@Kelly McLaughlin - the marks on that piece were not from me, it was an end cut in the scrap bin - yes, in the bin......

@Dabbler : I believe I have somewhat dodged a bullet and will be able to at least carry on with some other work - I took the assembly apart this morning. I was going to pull this part of the lathe apart eventually (again) to remake the fine/course selector shaft as it is somewhat disgusting and remake that bronze gear as my repair was just that- repaired but not permanent. I found something in my repair that must have been part of the failing process.

@Marc Moreau and any other Utilathe owners may be interesting in the following so bear with me as there are a bunch of pictures.

Removing the main shaft assembly starts with taking off the chuck and the top lid on the lathe. The main shaft is held in place by the friction fit of the bearings and the collar on the back of the shaft. This collar is used to pre-load the conical Timkin bearing at the front of the lathe. It screws onto the drive shaft and is locked with a set screw - this set screw has a piece of brass under it to prevent the threads of the shaft from being marred - be careful not to loose it!

loosen off the set screw and undo the collar. I put the lathe in the lowest speed to help lock it up and then using an appropriately sized punch or rod, turn off the collar. Mine came off easily as it is just loading the front conical bearing and should not be jammed up tight. If it is all jammed up tight it will take a few taps of a dead blow hammer on the turning rod to get it moving.

Once the collar is off, you can drive out the main shaft. It will move fairly easily with some solid dead blow hammer blows to the back of the shaft. Support the front of the spindle as you drive it out.

the front of the shaft will unseat from the conical bearing, once free you can then stop hammering and simply pull out the shaft by wiggling and making sure not to jam up the two gears on the shaft. They should slip off as the shaft is pulled out.

You can lift out the smaller gear. To get the slow speed gear out you need to pull out the speed selector shaft - I will not be showing that as my issue is with the gear cluster on the lower left of the picture.

There is a set screw that locks a collar on the fine/course selector plunger. Loosen it and remove the collar. The fine/course selector shaft can now be pulled out with the drive gear attached. The drive gear is pinned to the shaft by a brass 1/8" diameter shear pin. Held in place with a cir clip. If this is not brass - replace it with brass - I use a 1/8" brazing rod with the flux removed - works well

Note how crappy that shaft looks!! - this is why I was going to make a new one - it does have one difficult part - that round spring loaded key.....As the selector is pulled or pushed from fine - to course feed, that key is compressed into the shaft and then springs up into a key way in the gear that either drives the feed faster or slower. The gear I am after is a bronze one that drives the courser feeds from 4 to somewhere around 24 TPI. Having this shaft out now is good as I will make a measured drawing a reproduce it as far as possible on the lathe and then it will needsome milling for that key - there will be a bit of a fix to the way the key is fitted to make the shaft smoother in that area. Originally a hole was drilled right through for the spring and then a piece of brass strip was hammered in to retain the spring - I think I can mill a pocket for the spring, add a small bleed hole for lubrication and that will keep the shaft smoother.....anyway...

After this shaft is out you can reach under the large slow feed (60 Tooth) gear and pop it out with the spacer and washer. Then you can pull out the 25 tooth bronze gear that is causing me the issue -

You then have a pile of stuff on the work bench:

So - You will see that my gear did not "fail" in the sense that it is still looking quite intact. There is, however, an issue on the inside where I made my repair. I cut the key way in with an end mill and left it round and did not file the sides to square it up as I did not want to remove all the repair material. I had to bore this on the mill (see start of this thread). the rounded side was not enough to keep the spring key from collapsing under the load of 8 TPI cutting.

So, ugh, I do not have any material to make a new one at this time and I am back to the ships on Wednesday. I am taking lots of measurements. This gear is a 25 Tooth 16 DP 14.5 PA - I have those cutters. The larger slow speed gear is a 60 tooth 18 DP gear - don't have those cutters -yet......So, I will take notes on everything and then re-assemble things backwards steps. I filed the sides of the key way flatter and will insert the gear 180 so that the loading is on the face that was not tore up. I think what I will do is make a wide blank (like 3 gears wide) and then cut the teeth into it, properly key cut it , and then part off 3 gears for future. The gear is only 1/2" wide so it is not a lot of material.

I will stay away from threading at the lower feeds Until I can get this fixed 100% - as I am back to work Wednesday I can leave things and make up the blanks at work and then cut the gears when I get home in a month.....argh......

 

[YYCHM]

WOW I'm impressed! You certainly know your way around the guts of that headstock. How long did that tear down take to do?

 

[Brent H]

@YYCHobbyMachinist, if I didn’t stop to take pictures I would say I could have it apart in about 30 minutes. To go further and pull the speed shaft (necessary to remove the big 72 tooth bull gear and the lower bracket for the feed gear drive would take another 1/2 hour or so.
If you look at Picture 1 and 2 - in order to pull the speed shaft you have to pull off the motor pulley and then take off the bearing backer plate (6 Allen screws) - this plate also supports the seal for the motor drive shaft. Once it is off you can pull the speed shaft back. Then you pull the bearing off the shaft for clearance and progress from there.

I decided to just pack it in and I will make some parts on the ship so I don’t need to re-assemble to just disassemble again as I will need to pull the speed shaft if I replace all the gears.

looks like welding projects and some wood working for the next few days - LOL

 

[Marc Moreau]

Wow thank you for all infos nice pictures.

 

[PeterT]

Thanks for taking pics. Always interested to see the insides of these machines.

Was the stock gear also a bronze inner sleeve? (or brass or whatever the alloy is).
Are the stock gears steel? Hardened teeth or just cut?

 

[Brent H]

There are two gears in the assembly that, to me, appear to be bronze - the one is the one I repaired and is the gear that takes the course thread feed. The other is a small 12 tooth that is press fit into a 40 tooth gear. This gear provides the drive for the large 60 tooth fine feed speed gear.

The original gear I fixed should be just one piece. My pictures do not show the colour very well but both the little gear and the one I will remake have that more copper colour verses the yellow of brass. Both of the gears are also turning on a shaft all the time.

I am thinking the other gears in the chain are cast iron, not hardened and have that cast iron type finish and colour. The main drive shaft I believe is steel, but does not appear to have hardened gears or anything of the sort. The main bull gear is cast iron.

The shaft for the fine/course feed I believe to be just good quality steel - you can file it reasonably easy and lots of wear.

from the look of the shaft and the 25 tooth gear I will make, there has been past damage/repair - I would think that someone was changing feed direction on the fly - also there are multiple set screw dimples on the shaft in way of the stop collar. This is odd as there really is no adjustment after install but perhaps it was not getting secured properly for a while.

this shaft rides in 2 cast iron bores in the lathe. Both are submerged in oil and the shaft looks ok in those areas. Just looks terrible where the gears ride.

 

[Dabbler]

You might consider the possibility that your cast iron gears are cast steel... A way to cut costs in the 70s and later was to make stuff out of cast steel and then only finish what was needed. Making gears out of cast iron, or even maleable iron is very hard on your hobs/gear cutters due to included carbides.

 

[Brent H]

@Dabbler you could be correct. Further study of the main shaft shows that the D-1 end of the shaft is hardened and ground- kinda to be expected. The gear at the back of the shaft (25 teeth) engages with the fine/course gears. Interestingly this part of the shaft shows wear but the other 2 gears don’t show as much. Mind you it looks like the wear is more from partial gear engagement.

I will see what cast steel looks like on the market. Hmmmmm

 

[Brent H]

The update so far.....

Well, back at work of course so getting some lathe time in the evening to make some parts. Brought a tube full of shaft material and some other stock to play with.
Making a new fine/course gear shaft and setting up to cut the gear for a new course feed (the bronze one). This one I will mill out as a long gear I can then part off down to required thickness. Should get 3 gears out of the 2” piece I have. Also, since I had the lathe apart before I left I made up a measured drawing for the cross feed screw so I will make one of those as well.

The blank for the Fine/course shaft is a piece of 3/4” cold rolled steel and it has been made - just need to get it back to the mill to make the part for the spring backed round key.

The cross feed screw was started but I am going to make it again as the 9/16 - 8 LH acme threads came out fine at the end but ..... the original was threaded with a die and the threads just end on the shaft. There is no tool relief. I tried to do the same but it is hard to have your lathe going, engage the half nuts and quickly drive the cutter back to 0 on the cross feed. The first (or last) couple threads are not the best. This was first time using a carbide 8 TPI Acme threading tool - cuts well even running backwards for a left hand thread.

You can see that the first three teeth have just a little ledge from the tool being turned in and the depth of the root diameter is not enough to allow the nut to thread up. I did not cut that relief to start with (that was after) but you can see the lip just before the threads and how deep the relief is needed. (About 0.072” for an 8 tpi acme). This shaft will be 9/16 OD 4140 steel rod.
I am also making new shafts and cross feed nuts and some gears for the Cincinnati project. That project will be a separate posting because I left all my pics at home on another computer. - ugh! I was, however, very successful at making a new 1”- 8 TPI left hand ACME bushing that was shrunk fit into a bored out cross feed nut. That was awesome as the part is on the eBay for $650 USD!!!

I will get some pics when I make the cross feed shaft again to show the set up etc.
I have mandrels made up for the gear cutting so will show that as well in the future.

 

[RobinHood]

the original was threaded with a die and the threads just end on the shaft. There is no tool relief. I tried to do the same but it is hard to have your lathe going, engage the half nuts and quickly drive the cutter back to 0 on the cross feed.

It might be easier to out-feed from 0 at the end of the thread. No need for a thread relief then. Maybe turn down a little stub at the right hand side of your shaft (as you drew it in your sketch); OD less than minor diameter. Use it to hold the shaft in the TS. Run the lathe in reverse and feed towards the headstock (lead screw turning opposite to the chuck => LH threads). You could set a dial indicator for your Z pull out mark (after 7.800 inches length) or use the DRO.

 

[Brent H]

@RobinHood - if you are running the blank in reverse you would then have to either have your cutter upside down or on the far side of blank?

 

[RobinHood]

Yes, cutter upside down. Most lathes don’t have enough cross slide travel to cut from the back; some have rear-mount tool post provisions...

 

[Hruul]

This might be a complete "newbie" idea and might not work for what yours doing (and would depend on the size of the lathe used of course) but could you turn the lathe by hand and leave the half nuts engaged? I saw a video on this the other day from Steve Jordan on youtube. He was running a myford7 lathe, so obviously small lathe a lot easier to turn by hand.

 

[Brent H]

@Hruul - the lathe is a variable speed Colchester-Clausing 10 HP - in low gear it is brutal to roll over.

I will see if I can flip the tool - only issue is if there is enough depth on the holder to get it back to centre of the stock. Hmmmmmm

When I cut the second one (first one was the bad measure of 7” LOL) I machined a nice bit at the end to finish depth where the tool would run out. I could, I guess, slow everything right down and dial in but I think making a small relief area will be fine. The tough part is that the rod is only 9/16 and I have no follow rest to help with deflection. Gotta take small cuts.

also the lathe would probably cut on the back side except for #2 starboard ballast tank stopping the full movement of the cross feed. - its a bit to integrated into the hull to do much with (LOL).

for internal threading running backwards with the cutter is great. - anyway we will see what comes of it. - thanks for the information !

 

[Johnwa]

A center in the tailstock will help with the deflection.


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[Johnwa]

This might be a complete "newbie" idea and might not work for what yours doing (and would depend on the size of the lathe used of course) but could you turn the lathe by hand and leave the half nuts engaged? I saw a video on this the other day from Steve Jordan on youtube. He was running a myford7 lathe, so obviously small lathe a lot easier to turn by hand.

I often use that method on my 9” Southbend. I would like to attach a crank to the outboard end of the spindle but haven’t come up with a way to make sure it disengages should I mistakenly hit the start switch.


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[Brent H]

@Johnwa - yes always have the tail stock centre going - I am threading close to 8 inches of 9/16 4140 rod so she would be whipping about pretty nasty - one of the issues we have on board is that the lathe is in a corner - no other place for it - and it is parked with the one ballast tank bulkhead stopping full cross feed and the sewage standby holding tank maybe 6 or 8 inches off the back side of the lathe. We had to remove and re-locate the whole power supply for the lathe. You pretty much need a mirror to check the sump level of the gear box as the site glass is on the back of the lathe. Only way to manually advance the lathe would be to basically leave the gears all in play and then use the chuck key to haul over the whole assembly.

I don't think it is super critical if I leave a landing for the tool to go into - could just use the tool cutter itself to drive into depth, retract, and then just use that place to start threading.

I am getting decent cutting with the carbide insert at about 130 rpm - leaves a good finish and peels a decent chip. It does, however, mean that at 8 TPI you are travelling the length of the thread pretty quickly.

I am hoping to have some stock coming in to try out new threads in the next couple days.....hopefully that goes according to plan