Is it feasible to make a new spindle?

[Ray C]

If you have the skill to make a "perfectly" uniform diameter shaft and if you can intentionally cut a diameter to your exact specification then, yes, you can make a spindle. There's nothing special about them. Once the basic shaft is made (spun between centers), you can switch to using a jaw and center rest to bore it out. The long bore does not need to be ultra precision. You might need to do it in two steps, one half the distance each step. The bore near the chuck end should be cut undersized and the taper cut into it once it's installed in the gearbox. After the basic MT5 taper cut, you'd want to hand ream it with a cutter -which are available for about 75 bucks. Not including the time to assemble in the gearbox, the cuts could be done in a couple hours or less. After that, you'll need to mill any necessary keyway slots, drill/tap holes etc.

I'd be inclined to use a piece of normalized 1045 with an OD about 1/8" greater than needed. That will buy you adjustment time to get the centers lined-up. A heat treat with final rockwell around 40-45 would be frosting on the cake. If you go with heat treating, make the OD of the shaft 1 thou oversize and bring it back down with a tool post grinder. For that, you'll need to fit end-caps so it can be spun between centers again.

It just so happens I'm doing something basically identical but, it's not a spindle, it's for precision grinding hubs with a very precise custom internal taper. Since it's a custom taper, I'm also making the taper reamer out of tool steel.


Ray

 

[itsme_Bernie]

I'm with Bollie and Kd on this one- my Heavy Ten uses an adapter to go down to 5C collets anyway. Much easier than a whole new spindle, and keeps your options open for bigger through hole.

If there is enough meat left in there, you can even make it tapered, like mine, and not use keys or loktite, and tap it out when not needed.


Bernie

Why not make an adaptor for the spindle? That way you still hav the larger through hole if you need it.

 

[David Kirtley]

I am still learning about some of the different alloys. Why 1045 rather than something that turns easier like 1144? Just availability?

I'd be inclined to use a piece of normalized 1045 with an OD about 1/8" greater than needed.


Ray

 

[Ray C]

Availability but other reasons too. Most of the 11-series is 1117 and with low carbon, the material is springy like a marshmallow -but less so than A36 and 1018. Low carbon steels always seem to need a spring pass which blows the nice final finish. 1045 cuts clean the 1st time for cuts between 15 and 30 thou and they take a good spring pass if it comes to that. Too much guess work with 1117 and I rarely see 1144. Also, 11 series usually comes cold rolled which has a lot of internal stress. You won't be able to keep your OD dimensions once you start boring it. Thicker diameter 1045 is mainly HR which I prefer because it's closer to the annealed condition. I never intentionally purchase CR. You can see the stress busting out of it when you face-up a piece greater than 2". It looks like gear ghost rings but it's not -it's because of the way the cooler/outer surface compressed the inner core when it was formed.

Oh, also 11-series can only be case hardened. 1045 and 414x are my favorites... 414x would be overkill for a spindle.

Ray

EDIT: Just a quick note -and not meant to be nit-picking... 10 and 11 series are not alloys because the only metal in them is iron. Alloys (such as 41xx) have more than one metal -usually iron, chrome, nickle etc.

I am still learning about some of the different alloys. Why 1045 rather than something that turns easier like 1144? Just availability?

 

[David Kirtley]

Always good to be precise in language. Words mean things.

EDIT: Just a quick note -and not meant to be nit-picking... 10 and 11 series are not alloys because the only metal in them is iron. Alloys (such as 41xx) have more than one metal -usually iron, chrome, nickle etc.

 

[Ray C]

Thanks for not taking offense. It was not intended to offend.

Always good to be precise in language. Words mean things.

 

[Tony Wells]

It's not unusual to see 1045 used for parts where high strength alloy steels aren't justified because of expense and difficulty in machining. Although in larger cross sections it's not recommended for through hardening, localized hardening is common, as in flame or induction hardening. Some pieces, such as a lathe spindle, either can have gear teeth cut directly on them, where hardness as well as toughness is desired, or bearing journals or very closely sized sections where the hardness makes grinding more practical. Flame or induction hardening can accomplish this economically. Most any material will have residual stresses, and drilling a hole through a bar will guaranty some movement. In order to end up with a piece like a lathe spindle, careful planning of the cutting sequence is of paramount importance, especially if any heat treating is involved.

My personal choice would be to use a through hardening alloy steel such as 4140 or 4340, depending on exact configuration of the spindle. That is, if I were building a spindle. I think I'd try to locate a replacement first, then perhaps consider making some sort of adapter to use collets if I just had to. I'm not a big collet user on the lathe myself. Perhaps if I did more small parts I would be, but I wouldn't go to a lot of trouble to use them in the first place.

 

[itsme_Bernie]

I really appreciate all the knowledge you guys are sharing about metals. Almost no way to learn these things without words like yours, or many years experience (which I don't have). Definitely why it is an apprenticed and journeymanship based art.


Bernie

 

[Ray C]

One thing worth pointing out... If I intended to make this part and heat treat it, I would change the order in which the cuts are made from what was first described (which was written WRT the likely case that the user won't heat treat it). If heat treating were intended, I would bore it first, make sacrificial end caps so it can be spun then cut the OD slightly oversized.

As far as using 4xxx material... It's a toss up for this application. I personally don't feel that full depth hardening is needed for this. Also, there's a wide variance in cross secional areas on a spindle. The tube walls are maybe 3/8" thick while the face might be an inch or more. You need to harden with the thinnest cross-section in mind; otherwise, they will be too brittle. Aside from that, I think a spindle needs to be more "tough" than "hard". The parts that need to be hard are where there's a lot of user-contact (such as the spindle face) and MT hole -as well as any keyway slots. A beefy case hardening of 40-60 thou would be fine which can be accomplished with 1045 w/o external carburizing pastes, gasses etc...


In all probability, either material would be fine -heat treated or not although, I think some case hardening at the face area would be beneficial in the long run.


Ray

 

[ycroosh]

First of all, that you everyone for jumping in.
From the looks of it, getting a new spindle from Grizzly is not that much more than making one, by the time I get the steel stock, reamer etc.
It hasn't occurred to me to make a sleeve adapter, though.
One question, though: how would I make the insert perfectly concentric with the spindle? It looks like there is enough meet to cut a small taper, so would I use that to hold the sleeve true?

Thank you
Yuriy