RF30 alignment guide build

[DavidR8]

Major progress today.
Put on the brackets for the hinge heim joint.
Cut brackets for the head.
Drilled and tapped for M10 SHCS.
And put it all together.
Still need to trim the brackets off and then paint it.

Works amazingly well.
I noticed that there is some flex in the brackets so I think I will add some gussets.


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[Norseman C.B.]

How good is the repeatability you get with it ??

 

[DavidR8]

How good is the repeatability you get with it ??

I didn’t get a chance to do a proper test with instruments but I did quickly drill a hole, raised the head and dropped it back and the bit went right back in the hole.


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[NC Rick]

Nice work! That project was quite a nice "test" of a lot of machining, welding and fabrication skills. Congratulations on a job well done!

 

[DavidR8]

Nice work! That project was quite a nice "test" of a lot of machining, welding and fabrication skills. Congratulations on a job well done!

Thanks Rick, appreciate that!
I had fun building it. I definitely learned some things such as how to make multiples of the same part and controlling distortion when welding.


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[NC Rick]

Distortion control of welding isn’t something I have learned.

 

[mikey]

How good is the repeatability you get with it ??

This is what matters, Dave.

It isn't easy to figure out how to measure this, is it? The test indicator holder itself cannot move or you lose your reference so what and how do you measure something that is changing in vertical height? Whenever I see someone report numbers, I always wonder just how accurate they really are. The only structure you can reference off of is the quill and that assumes the quill is truly vertically placed in the head. Add to that what happens when you torque the head locking bolts - run out on the quill changes if you lock the top bolt first vs the bottom and vice versa, not to mention how much torque you apply to the nuts. We're talking about measurements in the low thousandths or hopefully in the ten thousandths so little things matter.

Looking forward to how you measure and report this out.

 

[DavidR8]

I spent some time trying to measure how capable this guide is at returning the head to the same location.
My process was this:
Raised the head to a height where quill could be fully extended plus another four inches.
Put a mag base with a thousandth's indicator to the right of the quill.
Extended the quill only as much as necessary to get the stem of the indicator against the quill.
Moved the X-axis till the indicator made contact.
Moved the Y-axis back and forth till I found the high point of the diameter of the quill similar to dialing in a 4-jaw chuck.
Zeroed the dial.
Fully extended the quill.
Locked the X and Y axis.
Raised the head to the maximum height while still making contact with the indicator. While cranking the handle the needle swung about 20 thou but settled back down when I stopped cranking.
Tightened the head bolts
The quill was within 1/2-3/4 of a tick off zero.
Slacked the head bolts and dropped the head to the lowest point possible.
Re-tightened the head bolts with the same result.

I snugged up the jam nuts on all of the heim joints and that reduced the deviation to about a needle's width off zero

I did notice that when cranking the head up (less so down) that the angle iron at the hinge was flexing maybe 1/8"-1/4". I think some additional lateral bracing would stop the flexing and likely any movement while cranking.

 

[mikey]

I snugged up the jam nuts on all of the heim joints and that reduce the deviation to about a needle's width off zero.

So, you're saying your set up can reproduce accurate positioning to about what, 0.0002-0.0003", depending on how wide the needle is? If so, that's pretty good, Dave!

 

[DavidR8]

So, you're saying your set up can reproduce accurate positioning to about what, 0.0002-0.0003", depending on how wide the needle is? If so, that's pretty good, Dave!

Thanks Mike.
I think that I can reproduce that level of accuracy. I want to do some more testing after I add some bracing but I think that this is an excellent design for us round column owners.