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Grizzly DF-1237G/G1003/Busy Bee Spindle/chuck Upgrade

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kb58

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I'm considering upgrading my Grizzly DF-1237G. I was leaning towards selling it due to a persistent oil leak, and "just because", but it turns out that while the seals are unavailable from Grizzly, they're common enough that even Amazon stocks them, so I'm hesitating selling what otherwise is a pretty capable lathe. This then led to thoughts of a full disassembly, cleaning, paint, swapping the lathe stand for a tool chest (can always use more storage), adding a backsplash (so no more cleaning behind it)... and upgrading the spindle. This last bit could be tough because word has it that the spindle nose has some odd thread size which is a mix of metric and English dimensions.

I'm posting this to see if anyone has gone down this path before. Apparently the spindle has an MT5 taper, so that's good. I looked through the Bison online catalog and found what appears to be an MT5 back plate (part number 7-915-0605) which bolts straight to their chucks. One problem is that it doesn't seem to be available, but requires more digging. Assuming I'm not overlooking something huge and it does fit, the MT5 taper adaptor means giving up being able to pass material through the chuck. While I hardly ever need to, it sure is convenient as an option.

The other approach is to do it the hard way, making a backing plate that screws onto whatever oddball nose the spindle has. Though much harder, it opens the door to being able to mount a modern D1-4 camlock chuck. The hard part is making an accurate backing plate, one without an unintended taper or wobble... So, what say you?
 

Dabbler

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First I own one of these leaky lathes... The spindle is 62mm by 8TPI (no, I am not kidding!)

I have a full set of seals, they are not expensive, but -- I have yet to figure out how to get the spindle out. One of our members has done it, but it looks like the job was done once before, so he had no problem - it came out easily.

On my lathe the bearings are a very tight interference fit, and they simply won't move...

Let me know if you plan to attempt it, and keep me posted on your progress if you do! One of my friends, Alan, had built several backing plates for his 12X37 with the same spindle. It's not hard, just takes work. Since it is my smaller lathe, and I'm getting pressed for space, I'm selling mine this year.

all the best!
 

Tozguy

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The other approach is to do it the hard way, making a backing plate that screws onto whatever oddball nose the spindle has. Though much harder, it opens the door to being able to mount a modern D1-4 camlock chuck. The hard part is making an accurate backing plate, one without an unintended taper or wobble... So, what say you?
That sounds like the 'fun' way. Go for it, its doable, should give you lots of satisfaction.
 

kb58

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I was just watching a "This Old Tony" video where he's making a new backing plate, and realized that I'm completely wrong about the MT5 taper. Not that it doesn't have one, but rather, I somehow got it in my head that the taper in the headstock was intended for holding the chuck.
 
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Tozguy

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So you have a lathe to look at but it was from the video that you realized what you have?
 

kb58

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Correct, my chuck is stuck on the lathe. In fact, if it doesn't come loose politely and something breaks, that could end the project before it starts. Anything else I can help clarify?
 

pdentrem

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If the chuck is stuck on, place a bar across its face between the jaws and try tapping the bar to spin the chuck off. If still stuck, try heating the mounting area of the chuck to expand it.
 

Tozguy

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Correct, my chuck is stuck on the lathe. In fact, if it doesn't come loose politely and something breaks, that could end the project before it starts. Anything else I can help clarify?
Have you tried removing the chuck? I don't see any risk of breaking something by removing the chuck.
 

kb58

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Have you tried removing the chuck?
I assumed that by saying it was stuck, I didn't have to say I tried removing it... my bad. Yes, I tried removing it, and... it was stuck.

I don't see any risk of breaking something by removing the chuck.
I do, potentially breaking off gear teeth if excessive force is needed to break it free. I think I'll try jamming a piece of wood in the gearbox to serve as a soft stop for the gears and see how it goes.
 
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Dabbler

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PLEASE DON'T jam wood into the gearbox. It puts significant unintended pressure on the gears - the is how to break either a bearing or a bearing race.

So, is there an obvious reason for it being stuck? rust? damage? What exactly have you done to remove the chuck? I went back an reviewed all your posts here, and I can't tell your level of of familiarity, and so I'm asking carefully and respectfully...

I can go over the procedure of removing the chuck, even if it is stuck, step by step if you'd like.

** I have had this lathe for 40 years now and I'm sure we can get the chuck off without compromising anything **
 

markba633csi

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Wood is usually a workable approach, or a length of old leather belt- something sacrificial to protect the gears. Be cautious when applying force- I would try also heating the chuck perhaps with some high wattage light bulbs or a heat gun
I feel that making a D1 adapter may be an exercise in frustration. Personally I would just make backplates to fit the existing threaded nose. If you can buy them semi-machined you will have a fairly easy time.
Mark
ps it's hard to advise someone on how much force to apply, some folks can stop just short of breaking things and others have no feeling for it at all (my brother for one) and go right past it with bad results. Try not to be like my brother. :)
 

kb58

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So far I've put a bar through the chuck and tapped on it pretty good. There is no rust, it's just on tight. I'm very familar with mechanical things, and know that with a long enough lever, a whole lot of torque can be back-fed through the gearbox, hence the request for guidance. That's a good idea about applying heat and will give that a try.
 
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Dabbler

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Mark, the use of wood or leather in an extreme circumstance is normally OK, but in this case there at 2 very small bearings that can be damaged. I am trying to encourage the correct use of the back gear/back gear lock that is intended for this purpose. He can't harm the gears using the correct procedure.

Right. First put the gearbox into back gear.

Second rotate the spindle in back gear until the the locking bolt can thread into the back gear body.

Third, use either the chuck key or a bar in the jaws to provide a surface to use a RUBBER hammer - not a 'dead blow eurothane' or other harder hammer. If you don't have a rubber hammer, you can cushion your chuck key with a piece of softwood.

When the back gear is engaged and the back gear locking bolt in inserted and tightened, the weakest link in the system is the back gear locking bolt - not the gears. There are 4 gears engaged to lock the spindle, in 2 pairs. If you use a 1 lb sledge or 16 oz framing hammer - on the wood - or a 1 lb rubber hammer, hammer so that the chuck rotation is counter clockwise. Keep persistent blows until it is free.

There is nothing to jam on the spindle, it is just being held on with old grease or possibly swarf. by repeated blows in this manner, the worst that can happen is to shear the locking bolt. You then have to extract the bolt and replace it with another, etc, until the chuck is free.

I know that there are machinists that are overbearing and tell you that 'their way' is 'the only way' - I'm not one of those guys (check my posting history), but... THIS IS THE ONLY CORRECT WAY TO REMOVE A STUCK CHUCK IN THE DF1237G LATHE - anythin else, including wood in the gears will result in damage, probably to the little gear bearings in the centre shaft.

Note: it is impossible to remove the spindle/bearings/seals until the chuck is removed anyway. kb58, I wish I was in California (for lots of reasons), then I could come over and assess/help you out directly.
 

kb58

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Thank you for the detailed response. I'll investigate further and let you all know.
 

Dabbler

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I should have said using a 4X4 of cedar or other soft wood on the corner hitting the key or rod is a good alternative to a rubber hammer - providing you don't wail on it.
 

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It looks exactly like my lathe! congrats! -- it is a really good lathe!
 

kb58

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In case this thread turns into something substantial, here's the manual in case others are looking for it.
 

kb58

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The plan to rebuild the Grizzly DF-1237G took a brief turn when a Clausing Colchester in good condition showed up locally on CL. Alas, it was apparently already sold by the time I saw it, as the seller did not return my message. A Hardinge HLV-H also showed up, and while I drooled over its specs, the $12,000 asking price is simply a bridge too far. Even if it wasn't, the reality is that I don't make anything requires such precision. Oh well, it's hard to not always want "the best".

Back to my lathe, replacement oil seals are onhand, so the teardown will proceed - and I'll stop looking at CL. I changed my thinking regarding replacing the chuck with a D1-4 chuck, because it'll make the process far easier. The new plan is to replace the existing chuck with either a Buck or Bison "Tru Adjust", using the existing backplate. This gets around having to fabricate a new backplate in order to gain what's probably a questionable amount of precision. The only question now is how much the backplate might have to be modified.

Speaking of the factory chuck, does anyone know what came with the Grizzly DF-1237G as-delivered? The reason I ask is that when I got it, it had an 8-inch 3-jaw on it. I kinda doubt that's normal. The chuck has no markings, so I don't know what brand it is, and the engineer in me has to ask, "How do I know that it's not already a high quality name brand chuck?" Well, I don't, but I think if it was, they'd proudly display their name or stamp on it. I also think that most people wouldn't make that change, but since I'm considering it, who knows.

Regarding the backplate, I actually have three! One for the 3-jaw, one for the 4-jaw, and another more generic one with a bunch of slots in it (which I need to confirm if it threads onto the spindle. I removed the 4-jaw backplate to see what it looks like. It has an 80mm bore that's a press fit into the chuck, but what's odd is just how rough the backplate threads are. It's as if it was threaded, then sandblasted with 1/8" sand, because the threads are very rough, like 60-grit sandpaper. Makes me wonder what the history of this backplate is. Anyway, this backplate is maybe 6" in diameter, with four mounting holes at mid-radius. The 3-jay backplate is 8" and has 3 mounting holes out near the edge. The third backplate with the slots is at least that big, maybe even larger.

Anyway, the whole chuck thing is for later, because in order to get there, the lathe has to be rebuilt first. Given some of the comments, getting the bearings out of the head could be difficult, and hopefully I don't ruin them or anything else.

I'm considering doing a YouTube series of the rebuild. I doubt there are very many people considering rebuilding one of these, but producing the videos would be good experience for me since I plan to do others (drawbar and car-related).
 

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Getting the bearings out will be interesting to everyone that owns that model lathe manufactured from 1979 to 1984, as we all have seal problems! So a youtube series will be very helpful! My understanding is that it is likely that the right bearing is going to be ruined in the removal. If they are a standard tapered roller bearing they should be available in the 200-300 range.

My 12X37 came with an 8" 3 jaw, and an 8" 4 jaw chuck, on backing plates. Mine are Taiwanese (noname) chucks and mine at least are as good as a Bison (but without the tru-adjust feature) Both of my backing plates have moderately rough threads - but I have seen far worse. My 3 jaw runs with .002 runout at 3/4" and .005 runout at 2". This is almost as good as a $1600 Pratt-Bernerd chuck, but not as good as the high-accuracy tru adjust PB 8" chuck that sells for $3000 CDN... I am thinking on how I can swap the 8" 3 jaw chuck over to my new 14X40 lathe and give away my 6" chuck (from the 14X40) when I sell my smaller lathe.

-- It is likely that your machine is a similar vintage as mine, and has the same chucks. Therefore you have a decent quality Taiwanese 3 jaw scroll chuck. More power to you if you upgrade to a Bison Tru-adjust! I'd love a 6" Bison 6 jaw tru-adjust myself - I just can't afford it.
 

kb58

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I won't spend any money on chucks until it's rebuilt and the runout of the existing chuck measured. If it's "good enough" (subject to definition), it'll be kept.
 
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