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Question on mill/drill traming.

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SonofHarold - Metal Carver

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I'll try and keep this short but a little back ground. I have one of the older HF round column mill/drills. ( model 24976)I know it has it's limitations but I am trying to get it to be as good as it can be. Finally got the spindle/quill re worked, and a simple DRO to have something for measruing the Z ( it had nothing) so it's time to dial it in and get everything square.
The other night I cut some shims and was just going to get started and see just how hard or fussy it was going to be and to my surprise it was much closer than I expected.
So I started trying to make it better. Ended up chasing the indicator around for more than two hours and a couple dozen different shim combinations. Made it a lot worse at times but the best I could get was within about .003-.004. I was using an indicator and a new disc brake rotor placed on the table and sweeping about a 10.5 inch circle. Question is; should I expect it to get much better with this machine? I was working alternately on both the side to side and the front to back and was kind of chasing it in and out a lot.... Right now fairly well snugged up it's off about 3 and half thousands on the Y and about 2 thousands on the X. It that as good as it gets or do I need to drink a big cup or patients and go back at it?
Thanks-
 

Technical Ted

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Yep, I agree 100% with Norseman... just run the indicator on the table top. If it was my machine, I would like to see it within 0.001" A lot depends on what kind of work you will be doing and what kind of tooling you will be using.

Ted
 

SonofHarold - Metal Carver

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That has a pretty small table and sweeping across the slots seem difficult, I think I found the idea of using the brake rotor on line someplace - maybe here(?)
I did try tuning the brake rotor 90 deg thinking there was some error in it because sometime it seem pretty consistant and others not so much but the readings on the indicater were the same +- a thou. or less.
But.... I did try going directly to the table and seems about the same as best I can tell, about .002 or a little less on the x, but sweeping acrross the slots make me question my accuracy too. Any ideas on that? guess I should take some pics of my set up.
So you would think that machine can be dialed in closer than I have it. Seems just reaching up to turn the spindle and touching the maching can move the idicator a thou or more if I am not gentle.
 

mikey

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I have an RF-31 so it should be very similar to yours, John. I agree with the other guys that you should use the table surface as a reference PROVIDED it is clean and free from defects. The reason for this is that it is what we mount our vise or work to and that is what we want to tram to.

As for acceptable tolerances, there is no standard for this sort of thing that I am aware of. Most of us want zero deviation in all axes, most of us can get 0.001" or less.

My column is trammed with precision shim stock and onion skin (precision paper shim stock). It is 0.0005" high in the front of the table and zero in all other directions. It took two days, two days, to get it there. I used a torque wrench set to 35 lb/ft on each column bolt to be sure that didn't mess things up and when I got the final shimming done, I loosened and re-torqued the bolts to be sure nothing changed. I admit that I haven't looked at it since so it may have changed. I'll have to go re-check it soon.
 

SonofHarold - Metal Carver

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So... I don't need a cup of fresh patience but maybe I should buy a case before heading out there? I did look around on the site a little more and found someone using 1-2-3 blocks and moving it from side to side when swining the indicator around. (?) When it warms up again some here I'll go try again, I shut down the heat a while a go out in the shop and we are going down to the teens overnite tonight so it might be the weekend before I warm up the shop again... unless I get bored ( I am sure you have no idea what I am talking about... just looking for sympathy... jk)
 

mikey

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Yup, patience helps. Look at it this way. The accuracy of every single face or edge you cut on the mill is influenced by how accurate your tram is, and tolerances stack up quickly. If you cut a side and use it as a reference for the next side then it will be off a bit, then a bit more, and so on. I figure its worth the effort it takes to get it right and then do what it takes to keep it right.

I used a Starrett back plunger indicator to get tram really close. The tip slides over the slots so its easy. Once I got really close, under a thou, I switched to a Compact 215GA tenths indicator and moved carefully over the slots to avoid damaging the indicator. Two days of that taxed my patience but I did it because it matters.

What is really frustrating is when I move the head, all that careful work goes out the window. We don't actually lose tram when we move the head; we lost that centered position from which tram was set. If we can return to that exact position the mill will be in tram again so the trick is to get it repositioned again. Bruce Witham of Australia came up with the True Line 88 to do exactly that. Others have used linear shafting to do the same thing, or laser pointers. I bought a True Line 88 to see if it does the job and when I have the time, I'll install it and review it for you guys here.

Unlike you, time is my issue. It is currently 76 degrees with a cool 17 mph Northeast trade wind so I'm comfy but don't have the time to tear into my mill right now. Is there such a thing as a gonad-warmer?
 

Norseman C.B.

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That tru line looks interesting.
I'm wondering if the UHMW will hold tolerance over time, I've made lots of
industrial roller shaft bearings with it but they do wear quicker than bronze the trade off being
cheaper to replace, maybe over thinkin here.......................:rolleyes:
 

Bob Korves

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So... I don't need a cup of fresh patience but maybe I should buy a case before heading out there? I did look around on the site a little more and found someone using 1-2-3 blocks and moving it from side to side when swining the indicator around. (?) When it warms up again some here I'll go try again, I shut down the heat a while a go out in the shop and we are going down to the teens overnite tonight so it might be the weekend before I warm up the shop again... unless I get bored ( I am sure you have no idea what I am talking about... just looking for sympathy... jk)
I do not like to use intermediate blocks of any kind when indicating something. Everything has a tolerance, is not flat or parallel, and using them as intermediates only confounds the readings. Use an indicator right on the table, and have it set up so the plunger can only go into slots or dings a few thou. Yes, it will bounce around some, but it will be measuring reality.
 

mikey

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That tru line looks interesting.
I'm wondering if the UHMW will hold tolerance over time, I've made lots of
industrial roller shaft bearings with it but they do wear quicker than bronze the trade off being
cheaper to replace, maybe over thinkin here.......................:rolleyes:
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.
 

darkzero

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I bought a True Line 88 to see if it does the job and when I have the time, I'll install it and review it for you guys here.
Awesome, looking foward to it even though I don't have a round column. Take your time but hurry up! ;)

My column is trammed with precision shim stock and onion skin (precision paper shim stock). It is 0.0005" high in the front of the table and zero in all other directions. It took two days, two days, to get it there. I used a torque wrench set to 35 lb/ft on each column bolt to be sure that didn't mess things up and when I got the final shimming done, I loosened and re-torqued the bolts to be sure nothing changed. I admit that I haven't looked at it since so it may have changed. I'll have to go re-check it soon.
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.
 

Aukai

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The guys in America don't feel bad for how cold it is here lately. Looks like a ski resort without snow with everybody bundled up around here. It's almost in the 50s in the morning, and doesn't get above 75 till the afternoon. OK back to regular programming.
 

mikey

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Brah, when these guys are seeing -50 degrees, we'll get no sympathy when we complain about +50 degrees! Let's you and I just enjoy where we live and quietly feel sorry for those frozen guys. :)
 

mikey

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Awesome, looking foward to it even though I don't have a round column. Take your time but hurry up! ;)
I'm gonna' indicate the head so I'm sure it is dead on center first, then re-check tram to make sure its good, then install the TL88. May take a little while - my project list is HUGE and I am waay behind.



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.
God, please let Will be right!
 

darkzero

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The guys in America don't feel bad for how cold it is here lately. Looks like a ski resort without snow with everybody bundled up around here. It's almost in the 50s in the morning, and doesn't get above 75 till the afternoon. OK back to regular programming.
Brah, when these guys are seeing -50 degrees, we'll get no sympathy when we complain about +50 degrees! Let's you and I just enjoy where we live and quietly feel sorry for those frozen guys. :)
It got down into the 30s 2-3 weeks ago, that's not normal for sunny SoCal! Well it happens every 4-5 yrs. It snowed here last week where it never snows. I didn't actually see it though.

Reminded me of this video about it. :D

 

Buffalo21

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I’ve used a brake rotor years, when I finish up, I rotate the rotor, 90 degrees, resweep and recheck the readings, I’ve never had to change a thing, some readings.
 

ThinWoodsman

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The guys in America don't feel bad for how cold it is here lately. Looks like a ski resort without snow with everybody bundled up around here. It's almost in the 50s in the morning, and doesn't get above 75 till the afternoon. OK back to regular programming.
Ten or so years ago, I went to visit an ex-pat friend living in Thailand. It dipped below 70F there one weekend, and all the young kids were out in the winter gear they'd inexplicably purchased and had been waiting for a chance to wear.

Same guy was telling me a story of explaining to a local (obviously not a very bright one) that houses in other places have heaters as well as air conditioners. "But why would you heat up a room when you're just going to have to use the A/C to cool it down again? Isn't that wasteful?"

Yeah, I kinda prefer having seasons. It passes the time :)
 

SonofHarold - Metal Carver

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Dropped the brake rotor and tried in directly, I think I also get a better more solid rig for holding the indicator. Do the pics look like the set up is OK? or should the indicator be at a lower angle more parallel to the table? At this point with out too much trouble I have it within a thou to a thou and a half (0.0015) the greatest error is in the nod (Y) and it tends to be low in the front. I notice it does not take much to push the head up/back a little and take out that error and figure any cutting is going to tend to push it in that direction anyway -(?) that is the .0015 and the largest difference as I sweep around. Big question is if my set up is OK per the pics? Thanks again! How about the set up for the vise?

20190306_130900.jpg

20190306_130847.jpg

20190306_135405[1].jpg
 

ThinWoodsman

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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

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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

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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

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... 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

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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

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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

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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

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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

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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!
 

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mikey

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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.
 
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