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Need to replace HLV-H leadscrew taper pin, any hints?

Long Tom

Stainless
Joined
Aug 21, 2011
Location
Fiddlefart, Oregon
It’s actually a Feeler 618 but the parts are in this case the same, I’m told.

Bought this machine knowing this pin was sheared. I was able to run it and put the EM gearbox gearbox through it’s paces so I’m guardedly hopeful that the pin did its job... but we’ll see. First things first, need to get the output shaft and leadscrew pinned back together. :)

If I clamp the half-nut I’m able to slide the leadscrew towards the tailstock far enough to expose the formerly-pinned area of the gearbox output shaft. The metal smeared pretty good when it sheared, but I was still able to, I’m pretty sure, ID the small end of the pin. I tried to tap it out with my small brass hammer and a punch, but it’s not budging and unless someone here assures me in forceful terms that a BFH is the proper solution, I’m not comfortable hitting it any harder than I was. Don’t want to damage a bushing or bearing on that output shaft, or bend the shaft itself.

The pin is in 3 pieces. My plan is to get that middle piece out of the gearbox shaft first. Once it’s out of the way I should be able to line it back up and tap out the smaller pieces in the leadscrew “sleeve”.

I’m thinking I’m just gonna have to drill out that middle section, and there’s good odds I’ll mess up the walls of the tapered hole in the process at least a little bit. So my current plan is to drill out until it hollows out enough to hopefully tap out. Then line things back up and re-ream the hole(s) with a #2 pin reamer and drive in a new pin.

My experience with damaged taper pins in machine tools is limited to rebuilding the clamping mechanism in my Webb lathe’s tailstock. A gorilla had done really dumb things in there... however the two taper pins he damaged weren’t sheared, just bent, so in that case I was able to get them out, re-ream the holes and put new pins in. So, the whole sheared pin thing is new territory.

I’m told the fallback move here is to just drill/ream a new hole entirely next to the existing one. I’m hoping to avoid that.

Appreciate any pro tips. :)
 
The best way isn't the easiest. I have had this happen to me a few times and the best way is to remove the shaft in the quick change. That way you can set it on V-Blocks on a Bridgeport and drill out the old pin, then slide on the feed screw and drill and ream the hole and use a new soft taper pin. It will be hard to line it up on the machine. You may want to file the QC shaft on each side of it. Many times on those small shafts it is easy to see the small side to tap it out. Use a short stubby punch and if you have to, grind a bigger one down. Then use a ballpeen. Use a bigger hammer so it doesn't bounce. Your right not a BFH, but not a mini one either. GoodLuck..
 
Agree with nailset for a starter punch. If you have one of the lead shot filled ballpeen hammers, use that for less bounce. Even a lead hammer will work well.
 
Machine a ring. You don't need the leadscrew for that. Drill and tap one side for a screw. Larger hole on the other side. Use the highest grade SHCS screw you can find. Slip the ring over the shaft and drive the pin out with the screw. Biggest problem is determining which way to drive the pin. Maybe file the surface and compare the diameters. Not sure this will work but it's way easier than taking things apart.
 
Messed with it some last night. It did not go well. Couldn’t get that middle piece to budge, and, after very gently filing away the smearing I was no longer certain which side was the small side. I had marked it with blue sharpie, but then, in a stroke of genius (sic) I thought maybe DyeChem would soak in and thus show the outlines of the pin against the shaft... did you know if the sponge top of your DyeChem is dried up, and you kinda pick at it with your fingernail the whole top pops off and the shit goes everywhere? Me neither!

Taking the whole thing apart is intimidating. Then again, so is plan C: hand-drilling a new hole at 90 degrees to the old one, then hand-reaming it... I know many many taper pin holes have been done like that but, yikes.

In “take a deep breath and regroup” mode, haha. The fellow at Babin said most guys just drill a new hole, go slow, be careful, etc....... it may come to that but... not yet.
 
It’s factory, so I doubt it’s got loctite, but heat is a great idea. I’ll try the heat gun.

Anybody know, roughly how deeply does the gearbox stub axle go into the leadscrew recess?
 
I’d have to take things apart to use the ring trick; I can’t slide the leadscrew all the way off the stub shaft from the gearbox, so no way to get the ring on there.

I’ll likely wander out there tonight and see if inspiration strikes... spent the day making parts on my other machines and, first paying work for the Feeler, made a batch of simple pins that I would previously had made on the Webb with the Bison 5c chuck. The Feeler was MUCH more pleasant for that job. Loved it. The pins are for a tool that installs/removes a soft copper stamped part so I hold a fairly tight tolerance on the pins to insure a good tight tool/part fit. Anyway the Feeler was, of course, nailing the numbers effortlessly.
 
I remember having to use more persuasion than I was comfortable with when I took apart the one on my HLV.
If you put a bit of acid on each side to enhance the perimeter of the pin and put a vernier next it, you should be able to figure out which end is smaller.


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About 20 years ago I sheared my taper pin off. I grabbed the hand wheel to prevent a collision and poof it was done. Too long ago to remember all the details but I did buy one tapered pin and a reamer. The pin sticks out about 1/8 on one side and just a hair on the other side. A long time ago, but I remember no real problem doing it. I probably used a small punch to get the remnant out of the gearbox stub, I like Conrad's idea, there would have been plenty of room on my HLV-H, evidently the Feeler bed stock casting is different.
 
I remember having to use more persuasion than I was comfortable with when I took apart the one on my HLV.
If you put a bit of acid on each side to enhance the perimeter of the pin and put a vernier next it, you should be able to figure out which end is smaller.


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I like this idea. What would you suggest for an acid?
 
Whatever you have..., I have a few different paint prep solutions that contain acid that would do the trick or some rust remover, such as “naval jelly”.


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I have muriatic (it was to put a patina on some stuff I used to make for a customer) but I don’t think I want that anywhere near important metal... hmm. Wonder what else I might have around... because SEEING where the outline of the pin is in the shaft is my current issue. It’s my fault; but there it is...
 
Agreed about keeping it away from the tools! I stored some nitric under my wood working gouges many years ago... That said, a tiny bit on a Q-tip on another piece of steel to see what it does is probably worth experimenting with.


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dilute the muriatic acid in half (stores usually sell it at 30ish % concentration), use cotton swab to smear it on lightly, it takes few seconds to work, you don't need to leave an open container for weeks next to the lathe for this, there is basically zero chance it will do any damage, if you want to be really by the book, dissolve few teaspoons of baking soda in a cup of water, dab a tissue in it and wipe the areas where you used the acid on to neutralize it

naval jelly is phosphoric acid, it will also work, but significantly slower

the pin on my HLV-H (KL1 actually, UK built) was 12-15mm from the end if I remember correctly, can check when I get home in 9-10 hours or so

to move the leadscrew more to the right you remove 2 screws from the bearing block on the right side, the block is also pinned, but there is enough of play in the design to allow it to be moved towards you enough so so that the pins either stay in the bed or come out with the block, once it is off the pins, move the whole deal to the right, it will give you plenty of access to use the "ring press" that Conrad has suggested

just to be clear - I'm not saying HCl is safe to keep around tools, without going into details about containers - it should be kept well away from metals, but few minutes to etch the shaft is perfectly safe and won't do any harm to anything

a side story, I bought some HCl at a hardware store a while ago, it sat in its original container in the shed for a year or two, I noticed stuff getting rusty in about 2m radius around it - went to pick it up and noticed damp patch under it, immediately poured it into a glass jar (only thing I could find quickly), and when I touched the bottom of the plastic bottle it almost fell off, the plastic it was sold in seems to have been corroded by the acid... I don't recall if I looked at the markings on the bottle to see which plastic it was, but so much for trusting manufacturers to use the correct stuff to store such things...
 
Thanks to all.

I went fishin (shrimping actually) this weekend so I’m not home... I’m going to try some mild acid to etch it BUT, as much as it pains me to say this, especially in the presence of some world-class machine rebuilders, I may be defeated. The end of the pin is bunged up enough that I might not be able to SEE the damn thing well enough to get a clean strike on it. In hindsite I think I needed to be bolder (bigger hammer) early when it was still a fresh surface.

I am going to give it one more try, but my mind has already turned towards making a jig to insure I drill straight and don’t break a bit trying to steer it if it drifts off course, and just drill then ream a new hole.

I’m embarrassed, and I don’t like failing, but at this point it’s feeling like the cleanest way forward if that makes sense.
 








 
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