New to me Harig Super 618

[RebelJD]

Harig Lubrication System
As I mentioned the original lube pump was missing and was replaced with a hand one shot oiler mounted on the side of the column. It was plumbed just as the original electric pump was and did provide oil to the column and ways, that is as long as you remembered to actually use it. However, I thought it best to go back to an automatic pump with a filter.

The original system is what I would call a "pump assisted gravity oiling system", not unlike a car engine. The pump sits in a sump at the rear of the machine and pumps filtered oil to the top of the column where it lubricates the down feed bevel gears and the thrust bearing. There is an oil site glass at the top of the column so you can verify oil is getting up there. Oil then runs down the lead screw lubricating the threads in the spindle housing and is then directed to the four vertical ways where it runs back down to the sump. Oil is also pumped to the saddle where is lubricates the table ways and then flows down to lubricate the base ways and returns to the sump and is recirculated. Here is a diagram of the system from a Harig sales brochure.

I found two oiling problems with the machine. There is supposed to be an oil cup with a lid on the rear of the machine for checking and adding oil, but it was missing. There is also supposed to be another oil cup, without a lid, sitting under the vertical column ways to catch oil and channel it thru a cavity in the base to the cross-feed nut. Oil would be wicked up to the nut via a piece of felt material. It appears that a previous owner moved the oil cup with the lid to the position under the ways thus preventing it from catching oil and likely led to the excess backlash in the crossfeed screw.

The second issue had to do with the oil channels in the saddle. When the saddle was machined grooves were cut lengthwise front to back and then the corners were filled with some sort of material to create a "moat" to hold the oil. There is a hole in the rear of the moat that provides a path back to the sump. On this machine one of the corners of the moat had been broken off, thus allowing oil to leak out and run down the front of the machine. I repaired the corner with some fiberglass filler. This is why it is important to level the machine as these moats are not very deep and oil will easily leak out if the machine is not level.

A replacement pump for the this machine is $950, which is way too much for hobby machinist budget. So, I did some research and decided on an inexpensive submersible pump for aquarium's, etc., I found on Amazon for less than $14. It is rated on 330 GPH and 25Watts and is small enough to fit in the sump. I was concerned that it would not be able to pump oil as well as water so I did some preliminary testing using transmission fluid instead of oil as it is thinner, and it worked fine.

The next thing I tackled was a filter. After looking at different options I decided a small automotive type filter that I could mount on the back of the machine making it easier to replace. So, I designed and machined a piece of aluminum flat bar (3/4" x 3-1/2" x 12") to work as an oil manifold and filter mount. It bolts to the back of the machine and has 4 jacking screws to help support it to the uneven casting. And of course a new cover to help keep stuff from falling into the sump.

Oil enters the filter on its outer perimeter, so the pump output connects straight through the manifold into the filter. Oil leaves the filter through the center hole and is channeled to the two adjustable valves you see at the bottom. (these valves are sold as air valves but work fine with oil). One goes the top of the column, the other to the saddle. There is a 3rd output from the manifold that allows oil to go directly back into the sump as a sort of bypass to help regulate the amount of oil going to machine. It turns out the bypass valve needs to be almost completely closed to allow enough flow to the machine. It's likely the filter is putting some restriction on the flow from the small pump.

I decided to stay with transmission fluid as the lubricant. It's inexpensive (did I mention I'm cheap), it is thinner than oil, and for the infrequent use of a hobby machine it provides adequate lubrication. So far it is working fine, all movements are very smooth.

I did modify how the crossfeed is lubricated. To lubricate the saddle oil is pump thru a cavity in the base and comes up under the saddle and is plumbed to the saddle via a hose. I tapped into this path and feed an adjustable valve feeding the crossfeed nut. There is a drain in the bottom of the new nut that uses the cavity that originally feed the nut and is now a return to the sump. It works very well.

In the picture above the line at the left will connect to the bottom of saddle but I'm running back into the sump as I adjusted the valve on the new crossfeed nut.

Whew, that took longer than I thought to document. But it is an important function that will help prolong the life of this machine. I hope others will benefit from seeing this.

Jim

 

[akjeff]

Wow, the price of those pumps has really gone up since I bought mine! Had they been the better part of a grand back then, I would have looked for an alternative too!

 

[ddickey]

Great write up. Luckily mine works fine. I even have a gallon of original Harig oil that came with the machine. I don't think I have a filter though.

 

[hman]

Wow, the price of those pumps has really gone up since I bought mine! Had they been the better part of a grand back then, I would have looked for an alternative too!

Here's one for about $20. Not sure if it's comparable, but it **is** a submersible pump:

Amazon.com

 

[RebelJD]

Great write up. Luckily mine works fine. I even have a gallon of original Harig oil that came with the machine. I don't think I have a filter though.

I think the original Harig pumps had a screen filter built into them.

 

[RebelJD]

Here's one for about $20. Not sure if it's comparable, but it **is** a submersible pump:

Amazon.com

I looked at those pumps also, but I wanted a pump with the intake on the bottom. It did come with some rubber feet that I should probably install to help keep it off the bottom where any debris may accumulate.

 

[akjeff]

I think the original Harig pumps had a screen filter built into them.

Exactly. The pickup on the bottom of the Harig pump has a screen to catch what doesn't fall out of suspension in the sump.

 

[RebelJD]

Harig Cable Drive Conversion
The rack and pinion table drive on the machine was a little loose, so based on some posts I saw on this forum I decided to convert it to a cable drive, which I understand was an option when new. While I had the table off, I drilled and tapped 1/2-20 holes in the bottom for the cable mounts. However, while I was assembling the machine, I realized the mount for the left side was too close to saddle and the cable rubbed on the casting. The casting boss for this bolt was not large enough to move the cable out so I had to make a cable mount on the side of the table. Not ideal visually, but it worked fine.

The right side was fine, and this is where I put the tension adjustment. My first attempt at selecting a cable was one from the local hardware store. It's the one pictured above. 1/16" cable with a total diameter of 1/8" with the outer jacket. I used a copper crimp sleeve (also from the hardware store) and put some heat shrink tubing on it. I used an electrical terminal crimper I have, and the crimps hold fine. I removed the gear from the shaft and installed a shop made hub that I put a light knurl on. The diameter of the hub is 1.200".

However, the cable kept stretching and I could not keep it tight. So I did some research, learned a little about wire rope and ordered a 10' length from McMaster-Carr. P/N 8930-T34, 1/16" wire with a total coated diameter of 3/32". It takes about 4' to do this, so I've got a spare length of cable. It is working fine now, no stretch and the movement is very smooth. The cable "threads" itself across the hub as the table moves so placement of the cable initially is important, or it will rub on the saddle casting. This is what I got from McMaster-Carr.

I also replaced the bearings on the shaft. I actually replaced bearings on the cross feed and elevating shafts also. Well, that's all for now. We got some snow last night so it's time to outside and clean the driveway.

 

[RebelJD]

New Harig 618 Electrical System

This machine came with a 3 phase 220vac spindle motor. As I mentioned there was no lube pump installed. The entire electrical system consisted of the power cord, a 3 pole on/off switch mounted on the base and the spindle motor. I don't have 3 phase power at my house, so I installed a small VFD to control the motor. I have two other machines in my shop with VFD's. The VFD is set to 60Hz so it is essentially a single phase to 3 phase converter. I prefer this method over a phase converter. The right side of the cabinet has a door and a 12" deep enclosure which is perfect for mounting the FVD. The rear of the machine had a cut-out for a 120VAC outlet which I decided to use for connecting the lube pump and a work-light (which I don't have yet). I decided to put in another cut out and wire it for a potential future coolant pump and vacuum pump.

The control switches for the spindle and the pumps and work light are now mounted on a new operators station I installed in the cabinet. I also included an Emergency Stop button and green light to indicate the lube pump is running. You cannot start the spindle unless the lube pump is on. I made the operators panel on my XTOOL laser engraver.

Here is the electrical schematic diagram and some pictures of the electrical panel, operators panel and the rear of the machine showing the 120VAC Outlets. The machine is wired for 220VAC single phase, 4 wire power. 4 wire power is needed because it includes the neutral required for the 120VAC outlets.

Thats all for now.

Jim

 

[RebelJD]

Harig 618 Magnetic Chuck rebuild

The last thing I did on this project was rebuild the magnetic chuck. I've never had one apart before, heck I've never owned one until now. The maker label was missing so I do not know the brand. It is a fine pole mag chuck which I understand is good for holding small parts, but perhaps not as strong as other chucks. There was no lever arm, only a square drive shaft sticking out, and it was metric so I'm assuming it was made outside the US. It did work but was hard to move back and forth. So I took it apart and found a lot of old dried grease and other nasties in there. There were several bolts missing from the bottom plate and I suspect it has been apart before. The biggest problem however was the hole in the casting where the staff ran was worn considerably. This was preventing the proper amount of movement to engage/disengage the sliding magnets. Its tough to see in the picture below right but the hole is enlarged so much it wore completely through the casting.

The shaft itself was hardened steel and was not worn significantly. So, I bored the hole in the casting a little larger, made a bushing and pressed it into the casting and then bored it to fit the shaft.

I then cleaned everything as best I could, put a little paint on it, greased it and put it back together. It works very well now. I found a piece of round stock in my parts drawer that had a square hole in it that just happened to fit the shaft. So I milled a hex on it and I use a wrench to turn it. I may make a real handle later, but this work fine for now.

The top surface of the chuck is not too bad. The bottom of the chuck and the top of the table had a lot of corrosion, so I cleaned them up with a flat stone and mounted the chuck. The only grinding I've done on it so far was to make diamond dresser from a round cast iron flange I had. The only grinding wheel I have currently is the one you see in the picture above that came with the machine. I installed it and ground one side of the flange. You can definitely tell the wheel was out of round by the grinding pattern it left. I mounted the diamond nib in the flange and then dressed the wheel. I then ground the other side of the flange and there was a significant difference in the finish. I plan to balance the wheel and grind the flange again to see if there is an improvement.

My plans are to make some test pieces and grind them at various locations on the table to check the accuracy. And then I'll grind the top of the table, and then to bottom and top of the chuck. All this after I get some practice on the machine of course.

Any suggestions on what type of wheels I should buy.

Thanks,
Jim