Wednesday, August 27, 2008

Rong Fu Report (RF45) - 3: Problems, problems

My old mill had a MT2 taper and the new one was R8 so I purchased a set of import end mill holders. None of them would go all the way into the quill and they appeared to hang up near the end of the groove. Either the groove was too shallow, or the pin inside the mill was too long. I sought out the help of a friend, MM. He had sent me a R8 spec and while the groove appeared pretty shallow it did, in fact, meet the specification.

We needed to tram the mill anyway so we decided to turn the head 90 degrees and take a look. Three large nuts needed to be loosened to rotate the head there was a small pin that prevented me from putting a wrench on the right hand bolt head and the nuts were tightened so much we had to use a rubber mallet on the wrench. The pin and a small nut is just visible above to the right of the large nut in the photo.

"What is this about?" I asked. MM showed no hesitation and unscrewed the little nut and pulled it out. Was it bravery on his part? Nah, just lots of experience working on mills. "It's a taper pin" he said and he carefully put it aside.

We rotated the head and there were two pins that fit inside the R8 groove to guide it. The one in the front was fine and the one in the back stuck out two hundredths. A little filing and every end mill holder in the set fit.

We rotated the mill back to apparent zero and he showed me how to tram it. It took only two tries and MM advised me, "This will never happen again. It always takes five or six tries to get it right." Before the final tightening he inserted the taper pin which fit perfectly. Apparently the Rong Fu folks tram the mill, drill a hole, and then insert a pin - a nice touch. In order to loosed the nuts holding the head in place we had needed to hit the wrench with a dead blow mallet. I think they were tightened so much at the factory so shipping would not change the tram.

Finally I was ready to make chips, but MM looked at the VFD and the motor wiring diagram and told me I had wired it incorrectly. My sequence was a plug to the disconnect, then to the VFD, which was wired to the mill switch. In other words, I was delivering 3 phase power to the switch, and then through the switch to the motor. The issue is electronic components in the switch that would eventually cause problems for the inverter, the motor, or both. In addition I could not use the inverter to change the motor speed in this configuration. The proper way was to connect the inverter directly to the motor.

The following weekend I rewired the VFD directly to the motor and discovered I could now change the motor speed with the inverter. Unfortunately this meant that the nice big red OFF button no longer worked and I had to use a tiny button on the inverter to turn the mill off. I knew there would be times I wanted a nice, big, hand off switch so I wired a large DPDT switch controlling all the power to the mill, and put it in a convenient spot. Eventually I will figure out how to wire the mill switches so they control the inverter.

Tuesday, August 26, 2008

Rong Fu Report (RF45) - 2: Setup and Inspection

I purchased the mill through J&L Industrial and had lots of conversations with them because the trucker lost the shipment and the situation got complicated. Their customer service is first rate and I have nothing but good things to say about them. During one of these conversations one of their supervisors said that they tested and lubricated these mills and when I checked all the grease points had fresh clean grease and the oil appeared very clean.

Visually, there was one cosmetic flaw in the table casting (L side of the table in the photo) and, l0oking at the inside of the column, there was some casting flash that was easily removed. In addition I was disappointed that the table handles were plastic rather than metal but, all things considered, the mill seemed well made and at the high end of import machinery.

The power to my garage is a long heavy duty extension cord connected to a 110V, 20 amp circuit. This mill comes with either a 1.5 HP, 220V single phase motor or a 1 HP, 3 phase motor. Due to my power limitation, I opted for the 3 phase motor because I could fit a 110V VFD inverter to it. I knew that DrivesWarehouse carried a TECO that would fit these specs. I called them first and got a sales person who was not helpful in answering my questions about how to set up the VFD for a mill.

Surfing the web I found a less expensive TECO at Dealers Industrial Equipment Their sales engineer explained that the JNEV-101-H1, was both newer and had more features than the FM50-101-C and, in particular, produced wave forms that were easier on the motor. His expertise sold me so I bought the VFD and mounted it on a board with a main disconnect, a heavy duty power cord, and a 110V receptacle for the mill X drive motor.

With some trepidation, I wired the mill to the VFD and when I fired it up, the VFD came on but the mill just sat there. What had I done wrong? Finally I figured out that the '5' on the VFD display was hertz rather than amps so I cranked it up to 60hz and the mill started running - that is to say it started running backwards. An easy fix - swapped two of the three hot leads - and it ran in the correct direction.

Monday, August 25, 2008

Rong Fu Report (RF45) - 1: Moving and uncrating

When I was deciding upon a mill I found reports from others very helpful. If you are interested in art and philosophy - stop reading now - this is about moving and set up.

The stand was delivered a week ahead of the mill and assembly was straightforward. The sheet metal seemed a bit flimsy to support the 800# mill however the stand was well designed to handle the weight. The stand is used for several models of mill-drills and came with instructions for an RF30 or 31. The shipping carton itself, however, had instructions for the RF-40/45. The top of the stand is a chip tray with gutters for flood coolant leading to a hole in the back where one can attach a hose. The top of the stand has 8 holes, 4 aligned for the RF30 models and a different set of 4 for the RF 40 models. There are rubber plugs for the holes that do not get used. Assembly was straightforward - no written instructions but the graphics were clear enough.

I paid extra for a lift-gate delivery so the mill was delivered to my yard. It was on a pallet, crated with mdf. The mdf was a bit scuffed, but everything was in order. I used a long 2 x 4 to pry up the crate, put some 2" pipe under it, and pushed it into the garage. A one person operation although it would have been a little easier to have a second person to place the pipe.

The next step was to uncrate the mill. It came assembled except for the table handles. The entire mill was in a big plastic bag. All of the the exposed metal had the usual grease which was covered with plastic sheeting. I removed all of this, wiped the grease off, and cleaned it further with kerosene. Kerosene is OK but not my favorite smell so I wiped everything as dry as possible and then oiled it lightly.

I started debating how to lift it with the shop crane without damaging the mill - or me! Fortunately the instruction manual had an illustration showing it should be lifted with a sling around the head.

I only had one, relatively short sling, so I put it right at the collar and when I lifted it, the mill tilted slightly to the back so I did not have to worry about it slipping out. While I maneuvered the shop crane, my wife graciously pushed and pulled the mill to align it with the bolt holes. Finally all the bolts were in place and secured, and then I remembered the 4 rubber plugs for the holes that were not used. I decided to push them through from the bottom rather than lift and then realign the mill. The way the gutters are designed I think the inside will stay dry however time will tell.

Friday, August 1, 2008

American Iron Guilt

My Benchmaster mill is just too small for my needs. The main problems are having only 9.5" between the spindle and the table and a 1/2 hp motor. Nonetheless, I am feeling some guilt over selling my venerable Benchmaster mill (true 'American Iron') and buying an import mill. Note that I am already being defensive by using the word 'import' rather than the truth, "Chinese'. The deeper truth is Taiwanese.

Anyone who knows about machinery knows that mainland Chinese mill-drills range from total junk to merely poor quality. It is not that the Chinese can not, or do not make high quality mills. Rather the home-shop mill-drills they export are driven by price, not quality.

The mill I purchased, a Rong Fu, is made in Taiwan and has a reputation for having decent quality, albeit, not as good as American mills. Of course, there are no American mill-drills and the only smaller American mills that exist are, like my Benchmaster, 40 to 60 years old.

Without further ado, here is my rationalization.

The Benchmaster has no quill, 1/2 hp motor, limited speeds via belts, and uses MT-2 tooling. The RF-45 has a quill, 1 hp 3 phase motor, 6 geared speeds plus a VFD, R-8 tooling, twice the Z Axis , has an X Axis power feed, and like the Benchmaster has dovetail ways. It may not have the rigidity of the Benchmaster but it is not 60 years old.

Does this rationalization carry the day? I will not be happy until I am milling away with half the passes and the same precision. Meanwhile, my wife says, 'Aren't you excited about getting a new mill?'