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| Building a follow rest... twice |
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| WeldingRod:
Of course I didn't take photos of the machining... Drat! Since I had it clamped to the mill table to do the bottom and take off the connectors, I cleaned up the whole finger slot. Just couldn't resist https://madmodder.net/Smileys/default/anim_32.gif And, finally, actually cutting metal! I needed to extend the threading on a 4" long 1/4-20 capscrew for the taper attachment, so that was my first customer. The three fingers in two planes worked really well, and I was able to easily cut another inch of threads on it. The funny shape of the top and bottom fingers are to give you a view of the cut and to clear the tool on the bottom. They might be version 2B... At least that didn't require a complete re-do. Oh, another thing I learned the hard way: roller fingers are a BAD idea on a follow rest. They gleefully roll chips in between the roller and the work, and push it around. Simple fingers push the chips out of the way... At least I learned that on the FIRST one! In case anyone wants to follow my path (at least the good part), the files are here: https://www.thingiverse.com/thing:2415678 If there's interest I'll type up the taper attachment. That one came together a LOT more smoothly https://madmodder.net/Smileys/default/nanarocks.gif |
| PekkaNF:
Very good writeup! I enjoyed reading, you explained nicely rationale of your construction and what you were trying to accieve. Sometimes I have a "bright" idea too and I decide make a tool, sometimes they work well and sometimes you see first time there is a "slight" problen: looks great but, no chance of working well. THis seems to inversely proportional to amount of time I used for finishing it and getting it right first time. --- Quote from: WeldingRod on August 10, 2018, 11:21:07 PM ---Did I mention that I drilled and tapped a hole in my saddle to make the bad one work? --- End quote --- Outch! --- Quote from: WeldingRod on August 10, 2018, 11:21:07 PM ---The second one went together much faster. An important trick I used: the main structure is two layers of steel. The fingers go in slots in one layer and the other layer has the matching bolt hole. I discovered that a steady rest actually wants to have the fingers offset so they can cross, and its nice to have three fingers. Thus, one of my plates has two slots and the other has one slot. I designed in a strip that closed each one of the slots so that they would keep their nice precision plasma cut widths during welding. After the welding was done, I cut off the connectors and finished things on the mill. --- End quote --- I was wondering why the two plates and you insist putting that much weld to warp it. That pretty much explains it. Warpage? Heat treatment? --- Quote from: WeldingRod on August 10, 2018, 11:29:50 PM ---Oh, another thing I learned the hard way: roller fingers are a BAD idea on a follow rest. They gleefully roll chips in between the roller and the work, and push it around. Simple fingers push the chips out of the way... At least I learned that on the FIRST one! --- End quote --- I kearned the same thing....if the material is that crabby you may use hardened fingers (counter intuitive, but works) or put a large bearing into steady rest and a cat on the pice to protect it. I on the other hand use brass shimstock or greased cardboard between finger and work piece, if the surface is soft. Does not work on thread, for those you need pretty hard fingers ot thread will start driving your cross silde. --- Quote from: WeldingRod on August 10, 2018, 11:29:50 PM ---If there's interest I'll type up the taper attachment. That one came together a LOT more smoothly https://madmodder.net/Smileys/default/nanarocks.gif --- End quote --- Please, that would be rally nice. I have not tried a taper attachment. |
| WeldingRod:
I TIG welded in short sections all over the piece, and allowed it to get really hot; both of those help keep down distortion. Preheating would have been better, but I didn't need that level of control. Hard clamping would also help. #1 moved no more than 1/16" over its 9" span after a full weld out. Sent from my SAMSUNG-SM-G891A using Tapatalk |
| WeldingRod:
Ran across a couple more photos! I milled the bottom of the follow, and relieved the middle. I had some fun scraping the steel (carbide scraper of course)! Yes, steel is a LOT more annoying to scrape than cast iron. I liked that you can see the pattern develop. I really didn't need to do it, but I wanted to...https://madmodder.net/Smileys/default/anim_32.gif |
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