What material should Camlock cams and stop bolts be made from?

[TorontoBuilder]

I need to make a new D1-3 cam to replace the one that a previous owner bashed trying to free the chuck. I fear that I'll have to use a screw extractor to get it out, but even if I got it out without further damage it is deformed enough to warrant replacement.

Compounding issues is the fact that most of the cheese head screws, stop-bolts and springs to affix the cams in place are awol. The one item I do have is not a separate assembly but rather a single machined screw and stop-bolt combo with no spring.

I understand that the cams are not hardened. But I have no clue about the tiny stop-bolts.

Suggestions welcome.

Pics will be forthcoming

What sort of ISO doesn't also speak to materials?

I also am not sure about how to interpret the diagrams for the stop-bolt dimensions. In the colchester manual the parts is 1161, so I guess the lower diagram is D1-3 bolt and the upper is the bolt for D1-4.

 

[Tom Kitta]

I have D1-3 and make all of my back plates.

The studs I make from soft steel. The cam locks are definitely not soft. I assume you mean the mechanism in the lathe head - the 3x cams that grab the stud.

 

[TorontoBuilder]

I have D1-3 and make all of my back plates.

The studs I make from soft steel. The cam locks are definitely not soft. I assume you mean the mechanism in the lathe head - the 3x cams that grab the stud.

Yes the spindle cams.

I know they're somewhat soft because they're been deformed from what looks to be the square head wrench. Let me restate my question. Does anyone have an idea of the type of steel I should use and the desired post machining hardness.

 

[Dabbler]

Does anyone have an idea of the type of steel I should use and the desired post machining hardness.

I bought a stick years ago of 4140 heat treated rod, centre-less ground (almost all used up now) it is heat treated to about Rc42 and is what I use for such projects. 17-4 is also available in the same condition, but wasn't available in Alberta at the time.

 

[Susquatch]

Yes the spindle cams.

I know they're somewhat soft because they're been deformed from what looks to be the square head wrench. Let me restate my question. Does anyone have an idea of the type of steel I should use and the desired post machining hardness.

I can't really help with the correct material. But I can sure feel your pain.

I have always assumed that the reason for those small T-Wrenches for the spindle is to avoid over tightening and ruining the cams. Yet I see guys gronking on them all the time. I don't believe it's necessary.

 

[TorontoBuilder]

I tried again tonight to get this to budge. Not a chance.

Normal cam

abbie normal

I haven't a clue how they managed to mangle the heck out of this, unless they used a cold chisel and 5 pound sledge.

I tried a screw extractor, but it is just a smidge too wide and can't get a bite to pull itself into the opening more. It slips out because the shoulders of the hole are rounded over in the counter clockwise direction. My other extractors are too small. I tried to drill it out, just briefly with cordless drill, the standard drill didn't seem to want to bite either.

so the cam is not mild steel, but not super hard either.

how to proceed will take some thought. definitely carbide tooling.

My brother suggested we custom grind square carbide blank into a make shift extractor.

My last ditch plan, to save the spindle and bearings from potential damage is to sacrifice the three jaw chuck. I disassembled the chuck face/jaws from the back plate and see that I can easily use a grinding wheel to cut cast iron boss into which the one jammed stud is screwed. A few cuts at the base of the boss from the retaining screw hole to the boss then vertically. Use the cut to insert pry and lever to crack the casting should do it.

I dont think I'd find a new backing plate to work with this chuck if that comes to pass.

 

[Former Member]

Just from your pic, I suspect one of 2 issues.

First being grit.....don't know what but it looks like there may be some.

Second, bolts have been turned the wrong way so when you think you are loosening them you are in fact further tightening them, unlikely but......it would explain why you can't loosen them.

 

[TorontoBuilder]

Just from your pic, I suspect one of 2 issues.

First being grit.....don't know what but it looks like there may be some.

Second, bolts have been turned the wrong way so when you think you are loosening them you are in fact further tightening them, unlikely but......it would explain why you can't loosen them.

could be grit.

I was thinking that based on some other "non-standard" work performed on this spindle that the past owner may have installed the studs at the incorrect depth and then over torqued the cams. They sure used a lot of force trying to free the cam up.

regardless it must come out. I shall not allow a repeat of my old VW camper van scenario where I couldn't get a flat tire off the rim for over 3 months one summer.

 

[Tom Kitta]

Oh wait, you have a chuck stuck there? Or shall I say half of it?

This could have happened when the stud was simply not locked - i.e. the little screw is missing.

I agree with Dabbler that it can be a 4140 steel and I was going to post here that I have no idea but if I had to make a cam it would be out of 4140.

As for stuck cam I would put in there a square bit and use impact to try to loosen it - but it may prove not possible.

I would also figure out where the stud is and simply drill where it should be to block it - does the cam move even a little bit with impact? Either direction? In the worst case you can always break the casting or try to drill out the stud - its not big, its 9/16 if I remember correctly.

 

[RobinHood]

The one item I do have is not a separate assembly but rather a single machined screw and stop-bolt combo with no spring.

Did you manage to get that out on the cam that is all chowdered up? It might give you a place to spray some penetrating fluid in and possible see what is causing the cam to hang up.

When I got my Colchester Master 2500, all cams were stuck - one really bad. It took the better part of a week the get the one freed up. Pulled the retaining components (1161, 1225 and 1200 in your diagram) out and kept flushing each hole with penetrating fluid every day. Also, used a close fitting, shop made, cam spanner and tapped on the handle in both directions multiple times a day. Nothing seemed to move at first, but eventually i could see more and more grimy stuff ooze out between the cam and its bore and they all freed up. Your situation may be different, but time can be your friend…

I would try to keep the square in the cam for as long as you can as you can apply way more torque on it than with any easy-out in a round hole. The easy-out may expand the cam and actually jam it harder in its bore. Perhaps “dress” the square with a burr, and make a custom tool for the now oversized square? Some heat might help as well.

 

[Susquatch]

I tried a screw extractor, but it is just a smidge too wide and can't get a bite to pull itself into the opening more. It slips out because the shoulders of the hole are rounded over in the counter clockwise direction. My other extractors are too small. I tried to drill it out, just briefly with cordless drill, the standard drill didn't seem to want to bite either.

I'd be inclined to try to make a better key and improve the key fit.

You can prolly use a small burr to flatten the sides of the hole. Then make a custom key to fit it. The original keys are almost always a really sloppy fit. Making a custom one might improve the torque you can apply by tenfold.

You can also use a high shear strength epoxy to improve the internal drive fit. Cover your custom key with Release agent. Fill the hole with epoxy and press it into the hole. Then babysit it and make sure you pull the key before it really hardens up and you can't. In case the epoxy slumps a bit, I'd be inclined to reseat the key periodically till it gets really hard, then leave it several days.

Use the time to keep soaking the cams with a deep penetrating oil.

The epoxy will never equal the strength of the original metal, but it will supplement it by improving the fit. You need every advantage you can get. Make sure you index the pin fit so it only goes in where it was molded to fit.

Then work it over time and let the penetrant work.

As you prolly already know,..... If all else fails, you might have to cut off and replace the spindle.

 

[terry_g]

Is there a chance they were turned the wrong way when the chuck was installed?
They will tighten and hold if turned the wrong way.

 

[Susquatch]

Is there a chance they were turned the wrong way when the chuck was installed?
They will tighten and hold if turned the wrong way.

I need to try this LIGHTLY.

I would not think the cam lock lines would line up if you tightened it the wrong way. But I'm not absolutely sure of that.

 

[John Conroy]

Wouldn't you like to find the guy who did that and feed him to the lions?

 

[historicalarms]

Im wondering if the pin setting was long & allowed the cam to over centered when being tightened creating a locked wedge in the pin cut-out, if that's the case I'm affeered that drilling will be the only remedy.

 

[Dabbler]

I tried a screw extractor, but it is just a smidge too wide

OHmygosh - no....

I dont think I'd find a new backing plate to work with this chuck if that comes to pass.

The chuck might be salvageable, but I'd never run it a max RPM - prolly 1/2 max...

As for stuck cam I would put in there a square bit and use impact to try to loosen it

yes!!

When I got my Colchester Master 2500, all cams were stuck - one really bad. It took the better part of a week the get the one freed up. Pulled the retaining components (1161, 1225 and 1200 in your diagram) out and kept flushing each hole with penetrating fluid every day. Also, used a close fitting, shop made, cam spanner and tapped on the handle in both directions multiple times a day.

Please try this. for months if necessary.

Failing all that: TIG weld a square stud to the cam. USING AS LITTLE HEAT AS POSSIBLE,, AND QUENCHING BETWEEN SHORT WELDS, and then use impact approach, again.

.....failing that, the cam can be drilled out. Then there is making the new one, of course. Inheritance machining has a good tutorial about making D6 cams.

 

[TorontoBuilder]

Did you manage to get that out on the cam that is all chowdered up? It might give you a place to spray some penetrating fluid in and possible see what is causing the cam to hang up.

When I got my Colchester Master 2500, all cams were stuck - one really bad. It took the better part of a week the get the one freed up. Pulled the retaining components (1161, 1225 and 1200 in your diagram) out and kept flushing each hole with penetrating fluid every day. Also, used a close fitting, shop made, cam spanner and tapped on the handle in both directions multiple times a day. Nothing seemed to move at first, but eventually i could see more and more grimy stuff ooze out between the cam and its bore and they all freed up. Your situation may be different, but time can be your friend…

I would try to keep the square in the cam for as long as you can as you can apply way more torque on it than with any easy-out in a round hole. The easy-out may expand the cam and actually jam it harder in its bore. Perhaps “dress” the square with a burr, and make a custom tool for the now oversized square? Some heat might help as well.

Absolutely I want to keep the hole as square as possible, but I actually need to dress the hole because they applied a ton of torque to the cam trying to back it out but kept no pressure on the tool to keep in tightly in the hole that they created a rounded ramp like deformity so that only a little pressure causes the tool to ride up the ramp and out the hole. I can turn clockwise and try to tighten the cam just fine.

Dressing the hole with a carbide bur and creating a custom steel square that is slightly over sized and ground to have an edge that will bite into the cam when torque is applied in the counter clockwise direction is another thought my brother suggested. I didn't think of an impact gun until someone mentioned it. I'll grind a couple of tools, and have one that fits the ryobi impact gun. It wont cause too much vibration that would affect my impossible to replace bearings.

I do have all the cam retainer holes wide open so I can fill the offending cam hole with any type of penetrating oil or other lubricant. My brother always cautions me to be careful in selecting penetrating oils since some have ingredients that can corrode critical parts if left in contact with the metals for any length of time. After my evaporust experiment destroyed a very expensive collet chuck for this lathe I shall be very careful in protecting this spindle. So lets hear peoples favourite choice of safe and effective penetrating oils.

The spindle only had one of the cam retainers and it is clearly one they made by grinding down a metric cap head screw. They ran a cnc grinding service so I'm positive it is their work. So I'll have to make up three cam retaining pin sets.

 

[TorontoBuilder]

You can also use a high shear strength epoxy to improve the internal drive fit. Cover your custom key with Release agent. Fill the hole with epoxy and press it into the hole. Then babysit it and make sure you pull the key before it really hardens up and you can't. In case the epoxy slumps a bit, I'd be inclined to reseat the key periodically till it gets really hard, then leave it several days.


As you prolly already know,..... If all else fails, you might have to cut off and replace the spindle.

Dude has the best suggestion for the initial plan of attack!!! I love it.

I shall 100% be trying this method first. I'll scuff the inside of the hole with a burr to provide a bit of tooth to resist sheer forces that try to debond the epoxy. Then I'll clean out the hole as best I can first, then use alcohol to degrease it. I have some longer ground glass fibers I can mix into the epoxy so is will have a bit more strength too and wont slump. I'll use a much better tool the the supplied wrench as the key.

The only way I'd be getting a new spindle is if I won the lottery. They're just not available in Canada. The only real viable plan I have if I pooch this spindle is to turn several up, and take them to a acquaintance in the tri-cities area who has a cylindrical grinder and beg him to grind them to finish dimensions. I'd actually have to turn the rough dimensions, let my brother turn to the dimension to send to the shop with the grinder. I'd have to do that in a hurry since my contact plans to retire soon. So let's just say that is not up for consideration.

 

[TorontoBuilder]

Is there a chance they were turned the wrong way when the chuck was installed?
They will tighten and hold if turned the wrong way.

I don't think so Terry.

I took macro photos of the mess, because it helps me see details better. I think I can still make out the stamped indicator mark at the lower right corner of the offending cam.

If you compare the two cams you can see the good cam is torqued less and the indicator on the cam is about 115 to 120 degrees, while the beaten cam the mark sits nearer to 135 degrees. Just too far.

 

[TorontoBuilder]

Wouldn't you like to find the guy who did that and feed him to the lions?

He and his brother retired to Texas. He also just casually had a automatic pistol sitting on his desk at his shop when I visited. I'll pass on attempting that LOL.