Having problem milling 120 degree sections

Good morning all

extropic; I believe this is what you requested, please let me know if I didn't fulfill your directions completely. My original ID measurement was off .005" the correct ID=.760" The off set for this exercise looks to be R=.040". See picture. I average all so I could give a clean measurement. Raw data is included.

Just for fun; this is a shot of the machine hub, I didn't remove it because I don't have a new roll pin if I mess it up at this time, sorry.

Thank you
 

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Thank you IschI99

My current limitation with producing some of the things being requested, as asked in post #30 is I am in Maryland 4 month of the year during the summer. The machines are in Maryland as well. I am a car buff that got tired of waiting on a professional shop to complete what I considered "easy to make" pieces I was taking to them. Days turned to weeks, weeks turned to months, COVID, etc.... I decided to expand my knowledge and experience and just figure out how to accomplish these things myself. I need to equip the Maryland residence with the necessary tools to provide the type of info that will be necessary for this hobby. At this particular time, tooling up has been a get it as you go/need. Not knowing anything about being in the machinist practice, I didnt anticipate any of the now apparent types of tools I needed. I took all printer/scanners, computers with me when I retired to Florida.

My apologies to everyone for the crud info but its what I have to work with right now. I will begin addressing each as I progress into this more. I just got the lathe earlier this moth the mill in June. I really have 3-4 weeks at it right now. Most of that time was spent putting DRO's on both of them. As I indicated in prior post, I was anticipating a 20-30min job to cut these handles. Not knowing what/why/how I was getting it wrong.

I hope everyone understands my appreciation for their expertise and willingness to share their knowledge with me. I miss things and have to re-read and respond as I catch my errors. Terminology I have to research and I try to be as accurate as possible given my resources at this time.

Thank you again
 
Ischgl99 said:
Is this what you are asking for? Note that I did not scale the drawing to the picture, so the dimensions there are just what size the sketch is and don't relate to anything in the real world.
Click to expand...

Yes, it is what I was asking for, in concept. I didn't realize you weren't working to scale.
Regardless, the graphic may serve to represent the concept I was trying to explain.
Thank you
 
want2drive said:
Good morning all

extropic; I believe this is what you requested, please let me know if I didn't fulfill your directions completely. My original ID measurement was off .005" the correct ID=.760" The off set for this exercise looks to be R=.040". See picture. I average all so I could give a clean measurement. Raw data is included.

Just for fun; this is a shot of the machine hub, I didn't remove it because I don't have a new roll pin if I mess it up at this time, sorry.

Thank you
Click to expand...

We get that you are a rookie with a desire. Everybody started somewhere and no apologies are necessary.
IMO, there have be a number of red herrings dragged across the path to success in this thread. It's important to tell good info from the other.
After all, it is the internet.
I think we have enough good info to risk cutting some metal (or whatever material you want to machine a test piece from).

One way forward is for me to think through the sequence of operations (SOO) that I would use, based around a rotary table.

If you think that would be helpful, respond in the affirmative and will post an SOO.

In the mean time, if you 'need' to make some progress, prepare some stock by cutting to approximate length and drilling the central hole .750. I know you measured the OEM part at .760, but I would shoot for a nice clearance to the shaft. Twist drills typically produce a couple thousandths oversized holes so try a .750 drill and fit check to your satisfaction. Bore to final size if you must. Face both ends. Your option on OD. I would probably use nominal 1.375 OD stock and polish it up with ScotchBrite. You may want to turn the OD for a the 'look'.
 
extropic said:
Yes, it is what I was asking for, in concept. I didn't realize you weren't working to scale.
Regardless, the graphic may serve to represent the concept I was trying to explain.
Thank you
Click to expand...
He didn’t initially post the dimensions of the handle, and the angles didn’t need that, so I didn’t bother to calibrate the sketch to the actual handle size. Based on your earlier post, I wanted to make sure you understood these are relative numbers. You should be able to scale the dimensions on my drawings with what want2drive posted above with his sketches.
 
want2drive said:
Thank you IschI99

My current limitation with producing some of the things being requested, as asked in post #30 is I am in Maryland 4 month of the year during the summer. The machines are in Maryland as well. I am a car buff that got tired of waiting on a professional shop to complete what I considered "easy to make" pieces I was taking to them. Days turned to weeks, weeks turned to months, COVID, etc.... I decided to expand my knowledge and experience and just figure out how to accomplish these things myself. I need to equip the Maryland residence with the necessary tools to provide the type of info that will be necessary for this hobby. At this particular time, tooling up has been a get it as you go/need. Not knowing anything about being in the machinist practice, I didnt anticipate any of the now apparent types of tools I needed. I took all printer/scanners, computers with me when I retired to Florida.

My apologies to everyone for the crud info but its what I have to work with right now. I will begin addressing each as I progress into this more. I just got the lathe earlier this moth the mill in June. I really have 3-4 weeks at it right now. Most of that time was spent putting DRO's on both of them. As I indicated in prior post, I was anticipating a 20-30min job to cut these handles. Not knowing what/why/how I was getting it wrong.

I hope everyone understands my appreciation for their expertise and willingness to share their knowledge with me. I miss things and have to re-read and respond as I catch my errors. Terminology I have to research and I try to be as accurate as possible given my resources at this time.

Thank you again
Click to expand...
We all started from scratch one way or the other, so no need to apologize. We will give you all the help you need, even if it takes time for you to acquire the tools necessary for the job. I do regular orders from McMaster-Carr since I never seem to have the tooling I need for the project.

I also understand and appreciate your situation with getting parts from machine shops, many don’t want to deal with retail customers and concentrate on business to business. I’m volunteering with a local robotics and STEM non-profit that has trouble getting things done for them quickly as well.
 
Thank you all

Just felt like I wasn't helping my situation or anyone by not knowing the ins and outs in providing info.

extropic, thank for the feed back; if you have the time, yes please, I would like to learn a good set up and sequence, I think I can learn from it and take away a process for future projects. My starting point with these handles was a 1.5" round bar of 6061 aluminum. Once I set up the lathe, level, test cut, etc.. I started to turn the stock to the dimensions on the original steel piece since I needed to duplicate that handle extension. See pictures. I purchased the tooling for the piece and a 17mm, .6693" drill for the ID to fit the shaft correctly. The .760" is the counter bore at the coupler splines/segments of the original part.That is what I have been referencing on all my dimensions as that is what the overlays are based on. The actual shaft D=.664". the bore in the original part is .675". My piece fits the shaft much better than the factory piece.

IschgI99; that must be rewarding, thank you for the feedback as well.

Not sure any of this info helps but I hope so.

Thank you all again
 

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For things that may take a few tries to get right. I often mill/turn test parts out of old 2x4s. Their somewhere between cheap and free for material, soft enough that you are very unlikly to break a tool, can be cut really fast, and you can just keep trying till you figure it out without breaking the bank in the process.
 
Thank you Flyinfool, I have a box full of those, didnt think they could turn on a metal lathe, I will certainly try that for my test runs, who can argue with free.
 
Now I need to apologize. I was previously ready to (help you) start cutting metal, however now I would like to nail down precisely the included angle of the slots. We're already in the ballpark at 67.03° but I have low confidence in that value. If we use 67° it may result in more wasted effort. Determining a high (enough) confidence angle can be a learning experience and (best of all) may justify you buying more tools.

I think the best way to go about it (within your current capability (machine tool & tooling) is to cut a few wedge pieces. Each one on the end of a piece of 3/4" diameter aluminum stock. Start by making a 67° wedge. Mark it so you know that wedge is 67°. If the fit in the OEM slot is excellent, BINGO. If not, make another wedge at a different angle until you are satisfied with the fit. Both walls of the OEM slot should be in contact with both faces of the wedge. No (or miniscule) wiggle at either end of the wedge.

I looked at Angle Gage Block Sets (AGBS) available to be purchased and I think they are too fat at the nose to combine 65° and 2°. I think any combination would have little engagement (if any) in you OEM slot. If you want to buy an AGBS to try, look for something like I've linked. The links are to show examples, not specific recommendations. However, the linked items are relatively low cost and easily available. Shop for desired quality/precision/configuration and price. You will find these tools useful as you pursue your machining projects.



If all that sounds to you like a good way to proceed, please keep us updated on your progress.
 
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