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Author Topic: BT30 spindle from scratch - with power drawbar and ATC of course  (Read 401790 times)

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Offline simpson36

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Re: BT30 spindle from scratch - with power drawbar and ATC of course
« Reply #100 on: September 06, 2012, 12:46:36 PM »
OK, two more pics and we're done. Here are the bearing retainer parts and the assembled spindle nose. All that is left are a couple of drive dogs. Anybody know if the dogs are hardened on a typical BT30 spindle?

I will need drive pulleys and a disc brake rotor for the top of the spindle, but I am note sure what arrangement I want  for those yet, so I suppose the power draw bar is up next. 



Re: BT30 spindle from scratch - with power drawbar and ATC of course
« Reply #101 on: September 06, 2012, 01:22:06 PM »
Steve,

It's a thing of beauty!  A few things I'm not clear on:

Are the 4 Philips screws what retains the lower bearing?

What are the two "dimples" on the inner perimeter of the (assumed) bearing retainer?

Don't know if BT30 dogs are hardened, but it certainly would not hurt.  I wouldn't think it would be really necessary, however.  In theory, there should be no movement between the tool holder and spindle, and even if there is, it'll be once per tool, and the dogs will make contact, then should not move again until the tool is removed and re-installed.

Can't wait to see what you come up with for a PDB!

Regards,
Ray L.

Regards,
Ray L.

Offline simpson36

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Re: BT30 spindle from scratch - with power drawbar and ATC of course
« Reply #102 on: September 06, 2012, 02:50:27 PM »
Steve,

It's a thing of beauty!  A few things I'm not clear on:

Are the 4 Philips screws what retains the lower bearing?
Yes, the screws, in part, retain the bearing. The screws shown are temporary until I grab some socket flat heads in that size. You know how it goes, I have ever size above and below . . .

I say 'in part' because there is also a press fit as well as being 'glued' in with Loctite bearing retainer.

Edit: oh yes, I almost forgot: mechanically there were also already pins thru the housing below the bearing.    

However, taken alone, and using only rough numbers because we are not even close to the wall, the bearing is rated around 10k and 4 of the proper fasteners will resist about 9.5k, so even without the press fit, glue, or preload on the top bearing, the lower bearing would be toast by the time the screws popped.

Quote
What are the two "dimples" on the inner perimeter of the (assumed) bearing retainer?

What hump?

kidding . . . those are just the remnants of the spanner pin holes. What is now the 'retainer' used to be the full plate with the labyrinth seal at the edge, so it had spanner pin holes for 'wrenching'. A new smaller plate takes its place, this time with the seal between the outer and inner disks.

« Last Edit: September 06, 2012, 02:56:54 PM by simpson36 »

Offline BR549

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Re: BT30 spindle from scratch - with power drawbar and ATC of course
« Reply #103 on: September 06, 2012, 05:58:20 PM »
Beautyfull job Steve, (;-)

(;-) TP

Offline BR549

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Re: BT30 spindle from scratch - with power drawbar and ATC of course
« Reply #104 on: September 06, 2012, 08:22:00 PM »
HIYA Steve I don't know how you are going to compare price wise but this is about what you are building.

http://www.tormach.com/store/index.php?app=ecom&ns=prodshow&ref=30505

(;-) TP

Offline simpson36

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Re: BT30 spindle from scratch - with power drawbar and ATC of course
« Reply #105 on: September 07, 2012, 06:38:44 AM »
HIYA Steve I don't know how you are going to compare price wise but this is about what you are building.

http://www.tormach.com/store/index.php?app=ecom&ns=prodshow&ref=30505

(;-) TP

I have been aware if the Tormac spindle for a long time. It was quickly eliminated for two reasons.

1) it is toy sized. I know it is difficult to tell from a photo, but for scale compare the BT30 taper to the housing size on my spindle and the Tormac. 
2) the Tormac has only a drawbar and no option for anything else.

Price? I don't think the Tormac spindle is equivalent to what I built. The price of the Tormac would get you the ABEC 7 bearing set for a 55mm shaft. I did a lot of bargain hunting and there is still more than the price of the Tormac just in parts and materials in my spindle. I would have built a new spindle long ago except for the $500 stud gripper. I have mentioned this before, asked about it, done extensive searching, best I eved did was I found one for about $400, and remeber this is just for the gripper fingers, nothing else.  I never found a used gripper and never found a ball type gripper new or used.

Probably I will not produce the spindle so I have not worked up a price, but it would be more than the useless Tormac toy and less than TECO or equiv precision sindles. I would sell the prototype for a reasonable offer only because I am contemplating going with a larger adapter size and it is not possible to recut the spindle for a larges adapter. Once I start using the BT30 spindle, I will be collecting more and more BT30 tooling which will make it a lot more expensive to switch to a larger size down the road. On the other hand it is always difficult to sell my prototypes and I have not listed the spindle, nor my 4th axis prototype. I know it is idiotic, but they are like my babies and I always want to keep everything.  :'(

Offline Hood

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Re: BT30 spindle from scratch - with power drawbar and ATC of course
« Reply #106 on: September 07, 2012, 07:42:23 AM »
Couldnt agree more, the difference between the two is night and day.
Hood

Offline BR549

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Re: BT30 spindle from scratch - with power drawbar and ATC of course
« Reply #107 on: September 07, 2012, 09:34:53 AM »
AH ok so what you really wanted was a 40 series spindle size. Now I understand. SHould be plenty of used 40 series spindle assy out there that just need a rebuild.



(;-) TP

Offline simpson36

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Re: BT30 spindle from scratch - with power drawbar and ATC of course
« Reply #108 on: September 07, 2012, 12:16:14 PM »
I don't just want a 40 series spindle, and I cannot use an off-the-shelf spindle. It is not that simple.  

What I want is an ATC. The spindle is just a piece of a much larger puzzle, as is the PDB. Actually, the ATC itself is part of a larger project. The concept of an ATC is not limited to swinging adapters around. A tool turret is also an ATC, in my view, and I am contemplating having both. Although in the 'mini-machining-center' configuration, the tools in the mill spindle can be single point tools for turning operations (see image below), my InTurn™ 4th axis' unique turning capability would not be fully served by a convectional milling machine ATC.  The 4th axis wants tools pointing at it. That is why I did the Horizontal Spindle project. I need the big spindle because it will hold not only single cutting tools for the 4th axis, but potentially also a tool turret. I have the static loading capability that I need, but BT30 is starting to look maybe a bit too small to hold a tool turret, There are other solutions to that problem, if indeed it becomes a problem, but most would require a new spindle design with a nose specifically capable of holding a turret, either by a larger adapter or a mount on the spindle shaft itself.

Hopefully that clears up some of the mystery.

Offline BR549

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Re: BT30 spindle from scratch - with power drawbar and ATC of course
« Reply #109 on: September 09, 2012, 11:57:30 AM »
YES that clears up some of the mystery.

Will this thing make coffee in the morning as well(;-).

Have you considered just adding the turret mechanism to the spindle housing and just index the spindle then relock the turret solid each tool change. You could add the index slots to the spindle housing then use the Power draw bar to lift the turret off the slots then use the spindle motor to rotate the turret then release the power draw bar to engage the slots again to lock it down.

That way you do not need a huge servo OR brake mechanism JUST to hold the turret in position

When NOT in lathe mode the spindle then uses a standard BT30/40 tool holder.  IF you are going to move up to 40 you might want to consider Cat40 as they are more common in the used market than BTs.

Just a thought, (;-) TP

« Last Edit: September 09, 2012, 11:59:35 AM by BR549 »