Overview
The Hermes 2 nose cone tip is made of stainless steel, is also and follows a 3/4 power series (hypersonic optimum) shaped shape, like the nose cone (although work should be done to determine how accurately this can be approximated by a more simple curve for ease of manufacturing). The nose cone tip has one bolt hole in the center, and two angled holes (5 degrees from vertical) on either side for thermocouples so that valuable temperature data can be obtained during flight.
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CAM File: Nose Cone Tip (SLDW16).SLDPRT **IMPORTANT
Lessons Learned
- Make sure that whatever stock you order is long enough to account for not only the part, but 1" or more for the lathe to hold onto. If the part is too short, it might get damaged in the chuck, and machining will just be more difficult overall.
- Use the correct feeds and speeds for steel. Ask someone who has experience turning steel, and do research online to confirm.
- Drilling into steel is difficult, especially with a small drill bit. Use lots of lubricant and slow speeds, and expect drill bits to break.
- Order extra steel rounds in case you mess up one of them
Dimensions
- Total length (not including step):
- Diameter of step
- Base diameter
- Bolt hole dimensions
- Angled hole dimensions
- Mass
Manufacturing Steps
- Make simple jig to hold the stock at an angle for the angled holes. We used an angle of 5 degrees for our two angled holes.
- Drill bolt hole and two angled holes (slowly, lots of lubricant!)
- Tap bolt hole
- Make CAM file from Solidworks
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- file. To do this, you may have to install a post-processor depending on the lathe you're using. (Download from HSMWorks and look in Program Files > HSM Works >
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- post
- Set proper feeds and speeds (this may require Google searching, and depends on the material you're working with)
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- Turn down outside of stock and step
- Load up program - this step depends on the lathe you're using (For ProtoTrak, save .cam file onto USB, plug USB into lathe computer)
- Make sure you have coolant flowing the whole time while turning or the part will get way to hot and deform
- Close the guard and start it up!
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- Make sure you're using flood coolant.
- Monitor closely, especially for the first few passes. Make sure tool doesn't collide with the chuck.
- Using a parting tool, part the piece ("parting" means cutting through it to separate your finished part from the rest of the stock), making sure that it is somehow constrained on the other end. As you get closer to cutting through the piece, slow the speed down so the part doesn't go flying as soon as it's parted.
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Manufacturing Attempts
| Date | Material | Result | Lessons Learned | |
|---|---|---|---|---|
| March 6, 2019 | Stainless Steel | Thrown from chuck | Need a longer shank (only had around 0.5" for the chuck to grad onto- want at least 1") |  |
| March 8, 2019 | Aluminum | Not awful | Surface finish bad, SFM increased to 240, cutter engagement lowered | |
| March 16, 2019 | Stainless Steel | Finishing pass ruined part | Tool nose radius set in CAM -> set to zero in tool setup, roughing pass needs positive stock to leave. |  |
| March 18, 2019 | Aluminum | Finish pass still bad | Tip tool path still glitchy, removed finishing pass | |
| March 19, 2019 | Aluminum | Good! | Slower, +flood coolant | |
| April 1, 2019 | Aluminum | Part fell out of chuck | Coolant insufficient? Cut depth too high? weak chucking? Shank turned first! |  |
| April 7, 2019 | Stainless Steel | Tip broke off, part still flyable | Make sure you're using correct feeds/speeds for stainless steel |  |
-Turn step
-Drill holes for thermocouples - hole was 0.125" diameter, 2.5" deep. Drill bit broke off in second hold (drilling into steel is hard)
-Turn rest of tip
Attempts:
- March 6: Steel - stock wasn't long enough, so part got damaged from being held too tightly by the step. Only had one hole for the thermocouple (which was linear, not angled), because the drill bit broke off in the other hole.
- Lessons learned: drill more carefully (lots of lube), order longer stock, turn aluminum prototype before starting on steel to avoid wasting steel stock
- March 16: Steel - everything went fine until the finishing pass (took off too much, left weird step at the base of the part)
- March 18: Aluminum - finishing pass was giving us trouble so we just made the roughing pass really fine (Fusion CAM didn't have an issue with the looping pass, but couldn't get the post processor to work)
- March 19: Aluminum
- April 1: Aluminum
^ Attempt 1 ^ Attempt 2 ^ Attempt 5
Aluminum Prototype
To debug the CNC process an aluminum prototype was turned. We set up a profile on the laptop for the ProtoTrak Lathe.
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