Question on mill/drill traming.

[ThinWoodsman]

Big question is if my set up is OK per the pics? Thanks again! How about the set up for the vise?

I'll let others speak more definitively on this, but right off the bat I would suggest making the indicator holder more horizontal (which entails lowering the quill towards the table) so you can sweep a greater distance. You want the greatest distance possible between the two points you are comparing (one to the left, one to the right of the spindle)

 

[SonofHarold - Metal Carver]

Awesome, looking foward to it even though I don't have a round column. Take your time but hurry up!



Haha, I think it took me like 4 days! 1 whole day to figure out how to support the head & column to insert & change the shims everytime. I used precision shim stock also. I got mine down to .0007" (low in the front) but I can manipulate it depending how much I tighten the head locks. Mainly it's the top one that affects it.

I just retrammed last week (tilt). Been years since put those shims in there and the nod is still the same from what I remember. My guess is yours hasn't moved either. I'm going to reshim again though, making sure the column gib is adjusted nicely first.

I checked out that True Line Kit, and found the Price at $400+ with shipping to be a little pricey. I am not sure my HF Mill Drill is even worth that much as it sits now.

To be honest, I don't move the head much thanks to the 5" of quill travel but it does move from time to time. What I want from the TL88 is for it to return me to my centered position, nothing more. Since it will see limited travel and limited use, I suspect the use of Delrin or UHMW material is a good choice. The vertical bar that travels through it is an accurately squared aluminum rectangular bar that is bolted to a bracket fastened to the side of the head and the Delrin block is anchored with a machined steel collar at the bottom. There is a hole in the Delrin that allows you to use a tensioning bolt to draw the sides of the channel tighter if needed.

All this thing needs to do is guide the head reasonably straight up and down and then allow the head to center accurately once the head bolts are tightened. My criteria for acceptable performance is for it to restore the head to centered position within a thou or less. If it does that then it is worth it.

I won't lie. I can easily make one of these contraptions but Bruce spent the time, effort and money to come up with this thing. I spent the money on it because it was the right way to do this and also because I wanted to review it for the HM membership. Since I bought it, I feel free to do an honest review, which I will do.

I looked at those also but at $400 (?) I am not sure my mill is worth it. I'd be happy to get much more than that for it as it sits. I only paid I think about $200-$250 for it from a friend who did much of the mods; power X feed and a DC variable speed drive motor. But I'll look for the review when you post it.

 

[SonofHarold - Metal Carver]

I'll let others speak more definitively on this, but right off the bat I would suggest making the indicator holder more horizontal (which entails lowering the quill towards the table) so you can sweep a greater distance. You want the greatest distance possible between the two points you are comparing (one to the left, one to the right of the spindle)

I understand a larger arc results in more accuracy. I set it there as the width of the table limits me, that set up sweeps within about 1/8" of each edge of the table which is only about 6" wide. I was trying to get both X and Y with one indicator set up. That is part of the reason I had been using the brake rotor which gave me about a 10 Inch circle... My main question here is the indicator itself accurate at that angle?

 

[mikey]

... should the indicator be at a lower angle more parallel to the table? Big question is if my set up is OK per the pics?

How about the set up for the vise?

The tip of the indicator is at too large an angle. This will introduce Cosine errors that will give you false readings. The indicator arm needs to be nearly parallel to the table surface. A quick search turned this up:https://www.cnccookbook.com/cosine-error-indicator-measurements/

You should also lower the quill and stretch out the indicator holder arm to give you more reach. The larger the sweep, the more sensitive the readings will be.

The vise set up looks fine.

 

[mikey]

I checked out that True Line Kit, and found the Price at $400+ with shipping to be a little pricey.

Gotta' agree with you that the kit is pricey and I don't think he'll sell too many because of that. If it works, the result will be that folks will just quietly pirate the idea and make their own. The kit is intended for older mills that are just not worth the cost. Moreover, the problem it seeks to solve is not a major one so the price is too high.

 

[RJSakowski]

One practice that I use when moving the head on my round column mill/drill is the snug up the center nut first. The I snug the top and bottom nuts. I then repeat the procedure a second and third time with the last time being to fully tighten all three nuts.

The reasoning being that if you tighten the nuts in a single operation, there is the possibility of resulting friction capturing a bias and skewing the head.

I did check to see if the tightening sequence affected tram and there was some difference but it was under .0005"/6".

 

[mikey]

Is you mill drill a HF model? All the Rong Fu mills have two bolts only, although I think three would be better.

 

[SonofHarold - Metal Carver]

The tip of the indicator is at too large an angle. This will introduce Cosine errors that will give you false readings. The indicator arm needs to be nearly parallel to the table surface. A quick search turned this up:https://www.cnccookbook.com/cosine-error-indicator-measurements/

You should also lower the quill and stretch out the indicator holder arm to give you more reach. The larger the sweep, the more sensitive the readings will be.

The vise set up looks fine.

Doing a little mental gymnastics on this... just want to make sure I'm thinking of this right....
Looking at the graphic on the cnccookbook site and if that is represented correctly for the example - the position of the indicator itself is at the same angle (0) and it is the angle of the tip in relation to the indicator which creates the error, or is it the angle of the tip to the surface being measured without regard to the angle of the indicator itself. The tip on mine has a ratchet or detents and can be postioned through more than 180 degrees in relation to the indicator. This is the only DTI I have, It is a Federal Testmaster. Do all lever type indicators have that feature?

 

[SonofHarold - Metal Carver]

Just located a PDF of an instruction sheet For my old DTI which answers my questions and has a table with a correction factor for various angles. More Tramming practice tomorrow. THNX!
Adding: thanks for the Ref to the CNCcookbook site! Never spent much time there cause I'd see the CNC and didn't think much there would apply to me. Looks like there is a lot of good info there tho. It is now bookmarked. You know I do love learning new stuff!

 

[mikey]

It's the angle of the tip that matters. Position the body the way you want but get the tip near level for that indicator. All DTI's should be able to do this.