Thread: Basic milling question

HI morrisman,
I just spotted your Thread whilst searching for or info on Tapered Gibs. Like you I have a DM45 Mill Drill mine is a TopTech branded one. Although I Tram the Mill, I've been finding the metal stock won't square up properly. Whilst doing some machining last night on a Bracket for a worklight for my Lathe, I noticed the facemill was cutting only on one end - Mill Out Of Tram. Tonight I pulled the Vice of the Table and Cleaned the Table. Then I checked the Tram which was out quite a bit. Whilst I was locking the Head up on the Gib locking wing screws (this was before I started to Tram the head) I noticed that tightening either of the Gib wing screws would put the Head out of Tram - one way and the other the other way (left and right).
I tried adjusting the Tapered Gib and got it a bit better, but still not right. I even backed the the bottom Gib screw right out and adjusted the top Gib screw till the Gib was tight (I pushed the Gib down towards the table by using the Screw as a driver). Then I backed the top gib screw off a touch and just screwed the bottom gib screw up tight then backed it off a touch. The Result of upsetting the Tram with the Gib wing Locking screws was much the same.
I was wondering whether your Mill might have the same problem. In that each time you Tighten the Gib wing locking screws up to lock the Mill Head the Mill Head goes out of Tram?.

Been there Steran50.

Do a search for BF20L mill from Ausino Engineering Supplies to see my problem, but I essentially get what you observe on my mill. My mill is an Optimum, but they are identical to the TopTech.

Try measuring the width of your dovetail column top, middle and bottom using dowel pins and see what you get.

These Chinese machines are woeful.

Originally Posted by steran50

HI morrisman,

I was wondering whether your Mill might have the same problem. In that each time you Tighten the Gib wing locking screws up to lock the Mill Head the Mill Head goes out of Tram?.

Hi I have been fortunate , my DM45 seems to tram OK. I have not noticed it moving as I tighten the column lock screws . I bought the machine from standaco , they trend to import thebetter quality gear . The main problem is the low quality castings , metallurgy wasnt big on the agenda of the asian manufacturers of this machine

mike

A lot of very handy information in this thread.

The links provided by Mike provided useful clarification. I have found difficulty with milling the ends of a block held horizontal in the vice. Maybe I was expecting too much, but the mill was not happy with doing this. I really liked the comment in the first page linked about only milling enough to sit the edge down on a parallel. I will have to try to remember that idea. That page also showed the use of a piece of round stock between the work and the movable jaw. I have often seen reference to using something soft in this position such as copper wire. This allows for variations in the work surface and as it will flatten somewhat, will not tend to roll when the vice is tightened.

I must be lucky with my mill, which is also a 45. I haven't trammed it for months and it still cuts with the 50mm face mill with just a light touch at the trailing edge regardless of which way the table travels. There is no detectable depth to this cut. It is just like a polish.

Dean

I am trying to figure out why the tram matters when squaring/facing a block? Say the head is out of tram on the X, and your feeding along the X, doesn't that just mean that your cutter will cut on the cutter (assuming face mill) closest to the table, but it will still be uniform the along the block? Say you have Y nod, and you feed the Y, then your nod is uniform and inconsequential. If you have Y nod and feed the X, then you have a problem depending on how you flip the block for the next face. You can flip it so that the nod is on the opposite side, and then you are square again.

It is my understanding that machinists tilt the head at times for facing operations and fly cutting so the back of the cutter does not rub. In essence giving a nicer surface finish.

I would have thought that tram matters in drilling, slitting etc. But facing, I am not sure on that one?

Originally Posted by variant22

I am trying to figure out why the tram matters when squaring/facing a block? Say the head is out of tram on the X, and your feeding along the X, doesn't that just mean that your cutter will cut on the cutter (assuming face mill) closest to the table, but it will still be uniform the along the block? Say you have Y nod, and you feed the Y, then your nod is uniform and inconsequential. If you have Y nod and feed the X, then you have a problem depending on how you flip the block for the next face. You can flip it so that the nod is on the opposite side, and then you are square again.

It is my understanding that machinists tilt the head at times for facing operations and fly cutting so the back of the cutter does not rub. In essence giving a nicer surface finish.

I would have thought that tram matters in drilling, slitting etc. But facing, I am not sure on that one?

If you feed in X axis and the tram is out on this axis you will cut a shallow curve, not a flat face. Picture an exagerated instance with the tram set to 45 deg. This is what you will get except much less curve.

Dean

Originally Posted by Oldneweng

If you feed in X axis and the tram is out on this axis you will cut a shallow curve, not a flat face. Picture an exagerated instance with the tram set to 45 deg. This is what you will get except much less curve.

Dean

Good point. I was aware that it could cut a small amount concave. I guess it just depends on how far out of tram it is, cutter size, and block size and how square the block needs to be. We are talking about a 45 (I have one) here so it is all relative. I should also make the point that if you put an indicator in the spindle and then touch the head, you can see more than insignificant nod.

Originally Posted by Oldneweng

If you feed in X axis and the tram is out on this axis you will cut a shallow curve, not a flat face. Picture an exagerated instance with the tram set to 45 deg. This is what you will get except much less curve.

That's the nicer possibility of what could happen - if you feed the cutter so it is centrally positioned you will get a concave surface. However, if the centre of the cutter is offset you will get that curve but one edge will be higher than the other (so if you were facing off the surface of a piece of 10mm square material and used say a 19mm cutter you've just "de-squared" your stock).

Michael

Originally Posted by variant22

Good point. I was aware that it could cut a small amount concave. I guess it just depends on how far out of tram it is, cutter size, and block size and how square the block needs to be. We are talking about a 45 (I have one) here so it is all relative. I should also make the point that if you put an indicator in the spindle and then touch the head, you can see more than insignificant nod.

I have not actually tried touching the head to see how much nod I get. I am sure I will get some movement. I should try it. It is worth considering for finishing cuts. Try to keep them small. I have pondered means to make the dovetail column more rigid to the base.

Michael I was going to mention what you said but I was too lazy. I knew someone else would chip in.

Dean

Originally Posted by Hornetb

Been there Steran50.

Do a search for BF20L mill from Ausino Engineering Supplies to see my problem, but I essentially get what you observe on my mill. My mill is an Optimum, but they are identical to the TopTech.

Try measuring the width of your dovetail column top, middle and bottom using dowel pins and see what you get.

These Chinese machines are woeful.

Hi Hornetb,
Thanks for the Reply. Measuring the Dovetail is probably a good idea, but until I get a large enough Micrometer I can't. The Gib could actually be pushed down to the bottom of the head where it finally firmed up and I couldn't turn the adjusting screw any more. I found this a bit odd that the Gib could come down this far, especially when I have never had to adjust it before. With the Gib coming down this far there is no allowance for future adjustment really without starting to cut the bottom of the Gib, because its starting to push the bottom adjusting screw out to far.

With the Gib down at the Bottom of the Head I can still wind the head up and down and it feels ok. My thoughts are at the moment that there is something wrong with the tapered gib. I am suspecting that the Gib is not thick enough and/or its angle is not correct. I haven't had any shed time tonight and am probably not going to get any shed time until friday or the weekend, then I can try and do some more investigating.

Originally Posted by morrisman

Hi I have been fortunate , my DM45 seems to tram OK. I have not noticed it moving as I tighten the column lock screws . I bought the machine from standaco , they trend to import thebetter quality gear . The main problem is the low quality castings , metallurgy wasnt big on the agenda of the asian manufacturers of this machine

mike

HI morrisman,
Ok so I got a dodgy one. I got mine from Standaco as well. Now that's a better name for the Gib wing screws 'Column lock screws' or even 'Head lock screws'.

Originally Posted by variant22

Good point. I was aware that it could cut a small amount concave. I guess it just depends on how far out of tram it is, cutter size, and block size and how square the block needs to be. We are talking about a 45 (I have one) here so it is all relative. I should also make the point that if you put an indicator in the spindle and then touch the head, you can see more than insignificant nod.

Hi variant22,
Are you touching the head or the spindle when you see the Nod. I'm assuming that the Indicator is touching something on the table like a Vice back jaw or the table T - slot.

Originally Posted by Oldneweng

I have not actually tried touching the head to see how much nod I get. I am sure I will get some movement. I should try it. It is worth considering for finishing cuts. Try to keep them small. I have pondered means to make the dovetail column more rigid to the base.

Michael I was going to mention what you said but I was too lazy. I knew someone else would chip in.

Dean

I guess the tilting of the head out of tram slightly is for cosmetic reasons where square to within x is not really necessary. I might have to square a block out of tram and measure the deviation from the center concave piece.

Dean you would be surprised by the nod you get. I was a bit annoyed a while back when I measured the nod by just a small amount of downward pressure from my hand. A cut with any amount of depth creates quite a bit of bounce unfortunately. One of the issues with the 45 is how the head connects to the column. I know Bob Warfield on CNC Cookbook has some good ideas on how to make things more rigid. Filing the column with granite epoxy mix is one way. But involves quite a bit of stuffing around. You really want to ensure the Z screw is accessible and the epoxy route could be troublesome. People also fill the base the same. You can also do a mod that consists of boring the head connection to the column and fitting a plug. I will be doing this mod sooner or later. I am doing a CNC conversion and it is part of the process. Some info from the aforementioned site is here: http://www.cnccookbook.com/CCMillZAxisMod.htm

Originally Posted by steran50

Hi variant22,
Are you touching the head or the spindle when you see the Nod. I'm assuming that the Indicator is touching something on the table like a Vice back jaw or the table T - slot.

I measured mine at the urging of those on CNCZone. I setup parallels on the table. Trammed the machine with a 0.01mm B&S indicator. I then did the test with just some hand pressure on the head and indicated the nod. It is irritating as I wrongly assumed that the head would be rigid enough to not nod with hand pressure.

The stuff by Hornetb is a little scary. I would not really want to do the dowel pin test as I fear I already know the result. I could share some more info on these machines but I do not really want to turn this into a bash the 45 thread. I got some great use out of mine for 18 months (and I pushed it well past the limit), but became disheartened. Cutting 7 BXA tool holders was the last straw for me. Took the best part of a day just to get a block down to size before I could even start doing work. I expressed my frustration the only way possible. I opened my ears and wallet. As such a Deckel FP2 now sits in my garage after being craned in from the street by a 60 ton beast.