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My Bridgeport mill uses 'quick change' 30 taper tooling, which instead of a using a drawbar to hold tools, uses a quarter turn nut on the bottom of spindle. I got rid of the spindle brake when I converted the spindle drive to an AC servo, so in order to change tools, I have to counter hold the drawbar while turning the nut - not very quick at all. On top of that, QC30 taper tooling is limited, uncommon and expensive. I have a bunch of BT30 tool holders that I could use on the machine, if I could get a drawbar through the spindle. Unfortunately though, it is solid. I bought a hollow QC30 spindle a few years ago, but it is too short by about 4". If I want to use BT30 tooling, I have two options. Drill a ~21" long, .6" diameter hole through the spindle, or lengthen the short spindle. I'm more attracted to the idea of lengthening the short spindle because I can theoretically do it myself, and the taper is in much better condition. I have lots of experience with TIG, but I've never worked on something that required so much accuracy and rigidity. I was thinking about making a windowed alignment collar that would hold the spindle straight during welding, and then welding it very slowly. My questions are:Would aluminum be a suitable metal for this windowed sleeve? Or should I make the sleeve from something more rigid?Would a sleeve alone be good enough to keep the spindle straight?What would be a good material to use to join the spindle together? 4130?Would I need to heat treat the spindle after welding? After heat treating would I need to regrind the spindle taper or bearing journal?What would be a good filler rod to use?The spindle in question:
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Originally Posted by Tightmopedman9
My Bridgeport mill uses 'quick change' 30 taper tooling, which instead of a using a drawbar to hold tools, uses a quarter turn nut on the bottom of spindle. I got rid of the spindle brake when I converted the spindle drive to an AC servo, so in order to change tools, I have to counter hold the drawbar while turning the nut - not very quick at all. On top of that, QC30 taper tooling is limited, uncommon and expensive. I have a bunch of BT30 tool holders that I could use on the machine, if I could get a drawbar through the spindle. Unfortunately though, it is solid. I bought a hollow QC30 spindle a few years ago, but it is too short by about 4". If I want to use BT30 tooling, I have two options. Drill a ~21" long, .6" diameter hole through the spindle, or lengthen the short spindle. I'm more attracted to the idea of lengthening the short spindle because I can theoretically do it myself, and the taper is in much better condition. I have lots of experience with TIG, but I've never worked on something that required so much accuracy and rigidity. I was thinking about making a windowed alignment collar that would hold the spindle straight during welding, and then welding it very slowly. My questions are:Would aluminum be a suitable metal for this windowed sleeve? Or should I make the sleeve from something more rigid?Would a sleeve alone be good enough to keep the spindle straight?What would be a good material to use to join the spindle together? 4130?Would I need to heat treat the spindle after welding? After heat treating would I need to regrind the spindle taper or bearing journal?What would be a good filler rod to use?The spindle in question:
Reply:When order my Bridgeport I paid extra for the quick change. Work great 👍 Dave
Originally Posted by Tightmopedman9
My Bridgeport mill uses 'quick change' 30 taper tooling, which instead of a using a drawbar to hold tools, uses a quarter turn nut on the bottom of spindle. I got rid of the spindle brake when I converted the spindle drive to an AC servo, so in order to change tools, I have to counter hold the drawbar while turning the nut - not very quick at all. On top of that, QC30 taper tooling is limited, uncommon and expensive. I have a bunch of BT30 tool holders that I could use on the machine, if I could get a drawbar through the spindle. Unfortunately though, it is solid. I bought a hollow QC30 spindle a few years ago, but it is too short by about 4". If I want to use BT30 tooling, I have two options. Drill a ~21" long, .6" diameter hole through the spindle, or lengthen the short spindle. I'm more attracted to the idea of lengthening the short spindle because I can theoretically do it myself, and the taper is in much better condition. I have lots of experience with TIG, but I've never worked on something that required so much accuracy and rigidity. I was thinking about making a windowed alignment collar that would hold the spindle straight during welding, and then welding it very slowly. My questions are:Would aluminum be a suitable metal for this windowed sleeve? Or should I make the sleeve from something more rigid?Would a sleeve alone be good enough to keep the spindle straight?What would be a good material to use to join the spindle together? 4130?Would I need to heat treat the spindle after welding? After heat treating would I need to regrind the spindle taper or bearing journal?What would be a good filler rod to use?The spindle in question:
Reply:First off................. https://www.hobartbrothers.com/2016/...w-alloy-steel/I have no idea whether the spindle is hardened, or not. Run a file across a non critical area, and see if it cuts.If you need to lengthen the thing, try lengthening it at the splined end. I don't imagine this end is as critical, and you can mill splines into a piece of solid round that you use to lengthen the piece. This would assure that everything's straight, because you've machined it.If your lathe doesn't have a big enough bore in the spindle to handle the business end of the spindle, make an adapter to clamp it in the chuck.......then hold the other end with a steady rest. This ought to be accurate enough to make your through hole. Then pop it on the milling machine for the rest of the work.Probably not the greatest idea, but Hell...............I'm no machinist.
Reply:There's too many unknowns to give solid advice I feel like but I'd want to know the following before I even thought about doing a job like that: What's the specific material typeWhat's the material's condition (can assume it's heat treated but to what hardness)What sort of runout can you have after weldingWhat can you lengthen the spindle with/what condition is that inWhat sort of pre/post heat and furnace options are available?The more you know the easier it is to make an informed decision on something like that, you can weld tons of things and get them to hold together. Can you do it economically and safely is the other two parts that I think people often fail to ask. Would aluminum be a suitable metal for this windowed sleeve? Or should I make the sleeve from something more rigid?Would a sleeve alone be good enough to keep the spindle straight?What would be a good material to use to join the spindle together? 4130?Would I need to heat treat the spindle after welding? After heat treating would I need to regrind the spindle taper or bearing journal?What would be a good filler rod to use?
Reply:
Originally Posted by Tightmopedman9
My Bridgeport mill uses 'quick change' 30 taper tooling, which instead of a using a drawbar to hold tools, uses a quarter turn nut on the bottom of spindle. I got rid of the spindle brake when I converted the spindle drive to an AC servo, so in order to change tools, I have to counter hold the drawbar while turning the nut - not very quick at all. On top of that, QC30 taper tooling is limited, uncommon and expensive. I have a bunch of BT30 tool holders that I could use on the machine, if I could get a drawbar through the spindle. Unfortunately though, it is solid. I bought a hollow QC30 spindle a few years ago, but it is too short by about 4". If I want to use BT30 tooling, I have two options. Drill a ~21" long, .6" diameter hole through the spindle, or lengthen the short spindle. I'm more attracted to the idea of lengthening the short spindle because I can theoretically do it myself, and the taper is in much better condition. I have lots of experience with TIG, but I've never worked on something that required so much accuracy and rigidity. I was thinking about making a windowed alignment collar that would hold the spindle straight during welding, and then welding it very slowly. My questions are:Would aluminum be a suitable metal for this windowed sleeve? Or should I make the sleeve from something more rigid?Would a sleeve alone be good enough to keep the spindle straight?What would be a good material to use to join the spindle together? 4130?Would I need to heat treat the spindle after welding? After heat treating would I need to regrind the spindle taper or bearing journal?What would be a good filler rod to use?The spindle in question:
Reply:Lots of great advice so far, thanks! Honestly, I didn't expect any replies...I don't think the spindle is worth much, and I didn't pay much for it, so if lengthening doesn't work out, I don't mind. The weld joint will be in the head of the machine, and the tool will still be retained by the drawbar. If the weld does fail I'll just break a bit and maybe lose a part - I don't think failure will be dangerous.
Originally Posted by farmersammm
First off................. https://www.hobartbrothers.com/2016/...w-alloy-steel/I have no idea whether the spindle is hardened, or not. Run a file across a non critical area, and see if it cuts.
Reply:If the addition is to the splined end,, no accuracy, or warpage concerns exist,,, if you simply weld on a piece of steel that is ~1/4" oversize,, then machine the shaft to match the existing diameter, and splines.There is zero chance that ANY common welding process could align an addition within any useable tolerance,, especially compared to subsequent machining,,If you really wanted to connect a splined addition to the existing shaft,,I would turn the shaft and addition so that there is a 2" overlap sleeve fit,, then, rather than welding, i would silver solder the joint.The long overlap of the joint will deliver better accuracy,, the silver soldering would reduce thermal distortion.Heck, at only 3HP,, you could probably machine a slight press fit, and simply drill and press in a couple roll pins.No heat would be necessary.
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Originally Posted by Tightmopedman9
Lots of great advice so far, thanks! Honestly, I didn't expect any replies...I don't think the spindle is worth much, and I didn't pay much for it, so if lengthening doesn't work out, I don't mind. The weld joint will be in the head of the machine, and the tool will still be retained by the drawbar. If the weld does fail I'll just break a bit and maybe lose a part - I don't think failure will be dangerous.
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Originally Posted by Thoriated Wolfram
If strength of the connection is not a concern have you considered brazing? It would eliminate a lot of the potential metallurgical problems that you're likely to encounter with TIG welding an unknown alloy like that. Is it possible the spindle could be made out of a high sulfur free machining steel? There's even more potential problems if it is. Case hardening could mean the base metal is normally a low carbon steel to make machining easier then they added the extra carbon to the surface to case harden. If so there's less worry about the weld than if the entire spindle is made out of tool steel, but you won't want to weld over the hardened surface with all that carbon it has. The weld can pick it up and you end up with lots of carbon in your weld which isn't exactly ideal. If that is a high Sulphur free machining steel then maybe a rod with more manganese in it than 4130 would work better? Like ER110-120?From Rolled Alloys "Specialty Alloy Welding" pamphlet:"High sulphur free-machining steels, such as the AISI 11xx and 12xx series, may also be subject to solidification cracking. This is usually a crack down the center of the weld bead, or crater cracking. A higher manganese weld filler is suggested in such cases."A stabilized grade of stainless might be better than 309 if there's a lot of extra carbon present as well. Like 321 or 347? I assume the stainless was to be used as a buttering layer? Good luck and let us know what you do/if it works or not.
Reply:I have no idea how the assembly goes together but could you make a threaded extension that goes on the business end? If not and you wanted to try lengthening it, I'd agree with extending the splined end. Possibly with a larger diameter piece and then cutting the splines after welding so it is as straight as possible. I just had another thought, could you tap the splined end and make a threaded spline extension? You could use red Loctite so it never comes loose unless you heat it. I wouldn't think there's that much pulling force on the shaft and the splines would definitely not turn unless the only part of them holding is on the extension. I'm thinking it could be like a hyd. cylinder that uses a bolt to hold the piston on. No welding which who knows if it would weaken the material or cause distortion from the heating and cooling that would be near impossible to get perfectly straight.
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Originally Posted by SweetMK
If the addition is to the splined end,, no accuracy, or warpage concerns exist,,, if you simply weld on a piece of steel that is ~1/4" oversize,, then machine the shaft to match the existing diameter, and splines. |
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发表于 2022-8-7 15:51:38