The drawbar rod. Used 1.2080 (I guess) steel. Hardened, tempered and grounded.
Continuing from this thread
Special thanks to @andypugh for his help and assistance.
I already made the gripper and currently I'm modelling for the rest. I'll add the detail later but if any of you have a question, suggestion, feedback, comment or anything. Just ask away
Here I am at the moment:
And the gripper:
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The drawbar rod. Used 1.2080 (I guess) steel. Hardened, tempered and grounded.
Here are some details.
- Lower bearings will be 2x 7009 (A or C) angular contact ball bearing. It is 45x75x16mm
- On the upper side I'll use one (or 2) 6008 deep groove ball bearing
- The belleville washers are D2010211. I'm using parallel groups of 3, 24 in total.
- Gripping force is 3kN and opening force is 5kN (more or less).
- Needed stroke is 4.2mm but I'll have about 6mm in total.
- Petals are C45 steel.
50x250mm 2080 steel for the main shaft.
If I'm not mistaken there are 3 type AC bearings with different contact angles. C (15°), A (25°) and B (40°). People ruse A or C bearings but I've never seen anybody used B. Which one would you recommend? I guess B is best if I want minimum play but since the B has a wide contact surface it is also the worst because it'll produce more heat.
50mm seems a bit small for the spindle nose. Have you thought about your dog configuration? I'm attempting to replace an r8 spindle shaft with a bt30 one and had a similar problem. Here's the spec I referenced:
http://i200.photobucket.com/albums/a...ine-taper5.jpg
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Not possible with my baby lathe Thanks.
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Suat
Proud father, C# developer, Model heli pilot, newbie free time machinist for hobby
Little changes on the design.
Do you really need 4 bearings on front end? What stiffness are you planning?
The 2 in the middle are just sleeve. Others are bearings. Its hard to tell from the pic tho. Should have colored them.
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Suat
Proud father, C# developer, Model heli pilot, newbie free time machinist for hobby
Here are some pictures of the BT30 spindle I bought from Aliexpress for reference. Hopefully they will be helpful.
The two bearings on the left are pressed up against a shoulder and then a inner race from a bearing is used as a spacer. Then comes the timing belt pulley and nut that holds the pulley on. The two left bearings are sealed. The angular contact bearings on the right are not sealed. They are configured like yours but only one spacer. Further to the right is the labyrinth seal and the nose piece that clamps the outer race of the angular contact bearings against the housing.
Here is the nose of the spindle shaft. The first picture shows the grooves that make up the most outside part of the labyrinth seal. Then the lighter colored aluminum ring is part of the labyrinth, it has a standing ring (going up in this picture) into an undercut in the steel of the spindle shaft above it. The second picture shows the nose ring, this is what clamps the outside race of the AC bearings. This is where some crummy work was done on my spindle, the aluminum tape you see was used to make up for parts being machined wrong. Where that aluminum tape is the aluminum ring from the previous picture is to be a press fit into. Someone machined the bore of the nose ring too big so they added a couple pieces of aluminum foil tape to bring it back to a press fit. The brown in the bottom of the nose ring bore is coolant and grease that has dried inside.
-Dan
Nice work Suat. How are you doing the labryth seals on your design?
Regards,
Mark
Regards,
Mark
Dan, thanks for posting these. Before I decide to build my spindle I contacted a few ali express dealers and asked for some details about what they sell. Steel grade used on each part, belleville washers and force for opening and clamping, the bearings used etc. They all answered almost the same. "Setel bearings". Like I'm stupid. So I decided to build it myself.
@Mark, I'm not there yet but I'm thinking to cut something like what Dan posted (see pic below) but also use a grease/oil seal. I'd like to take some recommendation here tho.
Azalin
For a labyrinth seal design the Flange in your photo is a very poor design & offers almost zero protection for the Bearings, here are some cutaway designs,I have made, that work very well, a regular Seal is not suitable for that end of a spindle, they will get damaged from metal chips Etc
These 2 Drawing will give you a better idea of what you need, to make for a labyrinth type seal, .1mm clearance is all that is needed on all faces where clearance is needed
Mactec54
Just to ensure that you are aware that flange is not the labyrinth seal. It is just provide the first channel which leads to the labyrinth seal. I think I have a nearly complete CAD model of my spindle, I will take a look tomorrow and create some screen shots of the cross section.
Dan
Is there a cad model available ?
Or one available elesewhere ..
I have another question. I'll send the main shaft for nitriding. As far as I know a nitrided metal has minimum deformation so I'll leave very small amount of material on the outside the shaft for grinding. Question is should I leave material on the taper cone inside the shaft (for grinding) too? And is it necessary for tempering the shaft? I'm asking because the steel I use is high carbon and I want it as hard as possible.