New Mill drill need some help and advice

[Ginettag20]

I used the new warco minor mill on Saturday for surfacing a piece of mild steel bar. I was using a face cutter that was supplied with the machine. This cutter looked very much like the machine that bored the channel tunnel, three inch diameter will 4 TC teeth brazed onto the periphery of the tool. I was running at low speed 100 RPM my thoughts being that this low speed may be more forgiving of my limited experience.

The tool was making a lot of noise as each one of the cutting teeth struck the work. At some point I must have put on to much cut, when the tool made contact with the work it dug in and the machine head also twisted on the column at the same time. This collision broke away part of the one of TCT.

I think that the speed I was using was obvious to low and I subsequent increased the cutting speed up 500 rpm.

The fine spindle adjustment on the machine seems very poor since it has so much back lash its hard to know how much cut has been put on. Does anyone have any advice for using these small milling machines and all the things I have thus far done wrong.

I have also had a problem with the column lock. Once the column has been locked it wont release and its near impossible to operate the rack and pinion for raising the machine head. Does anyone have a similar machine to this or had problems...

www.warco.co.uk/millers/minor.htm


Regards Chris..

[SteveW]

I've got a mill/drill type beast similar to the bigger Warco/Chester types and I find I have to be careful not to get too heavy on the cuts. A while back I had a go on a little Shoblin and was easily able to take 50thou cuts with an inch and a half tiped cutter and at a good feed rate. When I got home I quickly found a ten thou cut was more than enough on my thing.

I bought a 1" tipped end mill (two triangular screw-on TCT) and was never really impressed with it. I had a lot more success using the fly-cutter. My success rate increased when I started using a rightward TCT lathe tool in the fly-cutter holder, this being against a lot of advice here. It was pointed out that TCT wasn't well suited to the intermitant cuts of fly cutting. Well for three quid I was proved right. This gives a good finish using moderate cuts that can also be quite wide. On one piece of CI I found that it was only the TCT tool that didn't get its tip knocked off. It would cut while the HSS tool just banged into the job and lost its tip.

One major down side of these drill/mill things is spring in the column and eratic down feed on the quill. I can get a very good finishing cut just by adding a little weight to the top of the thing. As for the down feed, I've been caught out many times with the down feed back-lash. Generally, while using small feed increments I'd get a very light cut followed by a heavy cut. I also found (Granny suck eggs mode ON) always use the quill lock.

[Tim Bayliss]

Hi Chris,
I recently purchased a smaller machine, one of the mini mill/drills. I've found it'll only comfortably take 5 to 7 thou facing cuts on mild steel and use an ordinary 1" HSS end mill, which is the largest recommended facing tool size. If I had to face some rough stuff it may take a while but for m.s. it works fine. I have read that when using an end mill for facing it works smoother if you stone off the sharp edges of the flutes but I can't tell the difference.
Regards,
Tim.

[Ginettag20]

Thanks for the replies. Looks like I am going to have to take a bit more time and care using this machine.

I have to admit that when I got my Myford a very old and worn lathe, I had problems getting used to it. I had many years ago used large industrial machines and CNC without problems. I think that also many of the jobs I take on are just to big. I have been mainly making car parts.

The vertical milling book that I have bought features the Dore Westbury machine. I was hoping that I could tackle the projects featured. But after my poor start Im not so sure.

[Ginettag20]

Yes the quill lock is a must.

[IP]

Chris,

The downfeed of the quill on those things is held back against a 'Tensator' spring which will be on the opposite side of the casting to the downfeed control. My advice throw the tensator spring away and rig up a steel cable to the quill somewhere near it base will be a ring where the depth stop locates, this would be a good place to locate the cble end. Next run the cable via a couple of small pulleys over the top of the machine and secure it to a reasonable weight say at a guess a couple of kilos...the idea is that the weight is suspended in fresh air and the quill then pulls against gravity...that should sort out your downfeed problem.

Next throw away as far as you can the four tipped face cutter, these machines are not ridged enough for that type of cutter, instead use a fly cutter ground similar to a lathe tool for best results.

Also check the tightness of the gib strips, if they are loose chatter will be bought out on the machined surface not to mention an increase in backlash.

I also have one of the machines you refer to and excellent work can be done on one however, I also have a Tom Senior verticle mill which you wouldn't believe how much it cost it absolutely anhialates the otehr mill. Bearing in mind it only has a 1/2 HP motor, 100 thou cuts aren't a problem when needed.

I also used to have a Herbert OV which was donkeys years old that machine was built like a battleship.

Regards, IP

[conaglen]

Having had an Alpine Major mill/drill, very similar to the present Warco models, and struggled with its very poor cutting ability for some 18 years, I was amazed at the difference in performance a quite simple modification made to it. Not only will it now take a much heavier cut than before, but the finish obtained is ten times better.
I happened to read an article in Model Engineers Workshop No 19 entitled "Adding a flywheel to a mill/drill" written by Philip Amos. The problem with a lot of these cheap Asian machines is lack of weight behind the cut. OK the machines are heavy, but the rotating parts are not. The pulley on the cutter spindle is fairly large, but made of aluminium and mostly hollow on the inside. What Philip Amos recomends is to turn up a steel flywheel, perhaps made in a number of different sized discs, to fit inside the hollow spaces and of course to be firmly attached to the aluminium pulley. On a lot of these machines there is even room for perhaps a 10mm thick disc under the bottom of the pulley, and on my machine this bottom disc has a greater diameter than the pulley itself. The effect of the flywheel is to add considerably to the momentum of the rotating mass and to make this rotation far smoother as each tooth of the cutter does its work. If you need further details, please contact me. [e-mail]

[IP]

A friend of mine did the same thing adding steel dics to the pulleys on top of the quill.

He also split the front of the quill casting and put pinch pins in to improve the fit of the quill in its casting, the other thing he did was to add a three pahse motor and speed control system.

I would add that the guy in question is without a shadow of a doubt the best machinist I have ever come across [present company excepted!]

Regards IP

[Ginettag20]

Thanks for the good advice. I have heard about replacing the quill spring with a counter weight and I will give this a try. I think that I will invest in some HSS tooling as it has been suggested that I may get better results than using Carbide. I have bought a fly cutter but need to get a piece of tool steel for it.

I think that pulleys on my machine are cast Iron, I had to remove one when I need to remove the motor for transport. They were certainly very heavy.

Thanks again Chris

[SteveW]

Chris,

If you are buying a tool for your fly cutter consider a right pointing TCT lathe tool as per from Chronos or other suppliers. At three to four quid its worth the risk. Also, being bent (to the right) the cutting tip presents to the work better than you can achieve by grinding a corner of a bit of HSS lathe tool stock.

Also really worth buying (essential??) if you go down the TCT route is a small diamond lap. I bought a set of medium, fine and extra fine a while back and they're idea for tarting up the business end of any TCT tool. You don't need much effort either, just a couple of wipes will make all the difference.

They are also very good for that final finish to a standard HSS tool. You get to remove all the little grooves the bench grinder puts there and leave a very smooth and sharp cutting edge. This then gives you a very good finish on the work, more so than a TCT tool will ever give you.