[chich2]

Leeroy,
You and I have had the same toughts. I had also thought of hard chroming the quill up to size but this was going to cost me $890 bucks so that wasn't to be an option. You can very easily purchase ready to go Honed hollow steel tube for making hydraulic cylinders. I was thinging of sleeving the head with a steel bush of this material but that is no good as steel on steel will have bad wearing prpoerties. One option is to bush it with brass so for $150 Inc tax I purchased a piece as described in my previous post. When it comes time to bush the quill I will skimm the OD of the bronz to size, remove the entire head from the mill and bolt it to the cross slide of my lathe, right through it I will place a 70mm piece of high tensile bar between centers as a long solid boring bar. This boaring bar will hold a cutting tool. Using the lathe to spin the boring bar horizontaly I will bore out the inside of the head to siut the OD of the bronz Bush. I will then insert the bush into the head with a chemical lock like "loctite" without moving the head on the cross slide. After that I will bore the inside of the bush to suit the quill. With the length of bronz I have it should pick up the bottom web the mid web and also the top web where the pulley is mounted. After that I will mount the head to the table of my mill and use the horizontal axis to bore out the pinion and lock holes. I would have normally done all of this job in the mill but the Y axis doesn't have enough travel.

A very easy solution to this entire problem provided your quill is straight, smooth and parallel is to use a liquid filler and simply fill up the inside if the head with putty to suit the quill. An excellent product for this is MOGLICE. Examples of it can be seen at http://www.moglice.com/ If you take a look in their "Application Examples" and take a look at "Ingersoll Quill Bore + Elevating Nuts" you will see what I mean. All you have to do is clean everything up, plug up your holes, spray the quill with release agent and put it in the head, inject the moglice in and hey presto..... a perfect fit.

I have no idea what the product costs But I do know someone who has used it many times before and swears by it's accuracy. It is a very attractive solution. If you use a filler or bush it you will retain full travel in the quill.


For your question on the Z axis drive mechanism I am going to use will consist of the following;
I will bolt the head to my table with the quill center axis straight to and square to the column of the mill. I will use the horizontal spindle to mill the side of the head flat where the stop start switch is on the HM-52. This flat surface will be parallel and square to the quill. (I will later include the stop start switch to a movable boom) To the side of the head I will then mount my servo motor and drive mechanism. I will make a large solid steel clamp that will firmly hold the fat part of the quill. It will be a tear drop shape when viewed from the top. The pointy end of the teardrop will have a tube connected to it which contains the lead nut at the top. The motor mount which is bolted tight to the head will also hold 2 preloaded annular contact bearings firmly holding the Z axis lead screw in place. The way it will work is the motor and lead screw will stay stationry to the head and as the screw turns, the nut (anti backlash once again) in the tube will push the tube up and down. The tube is connected to the large quill clamp so therefore the quill will go up and down. All the thrust will be on the 2 annular contact bearings and the lead nuts......... Simple!

I have designed Z this way beacause if I wish to use my mill as a manual machine all I have to do is put the coarse feed handle back on, realease the tube from the Quill clamp and away I go.

Cost so far for my conversion has been $100 each motor times 4, $60 each encoder times 4, ($160 24volt 20amp servo's is CHEAP!) $45 each axis for belts and pulleys times 4

Hope that has not put your head in a spin!

Chich

[leeroy]

G'day Chich

It's funny you should mention hydraulic cilinder tube...
Ever heard that saying "He just got lucky.." Well today it happened to me. I was searching through the offcut rack at work today for some material for a job and literaly triped over a 500mm long offcut of 90mm Dia ground chrome bar!! (we often do repairs/rebuilds on hydraulic cilinders etc). I raced back to my tool box for the Mike and guess what.. 89.995mm, parallel within half a hundreth over the length i need!!:rainfro:
A quick chat with the boss and for $80 it was a done deal. He also said that it was a readily avaliable size too so mabe this is an option for you also..
So now i'll machine off the chrome for 50mm on one end, press on and weld a collar and then drill full length and bore for the spindal bearings. Fortunatly, i have access to a big vertical TOS at work so i can cut some new rack teeth and hey presto, new Quill.
I think this will be a pretty tight fit though so mabe some honing / lapping of the bore to get the fit right.

As for the z axis drive, i like your idea. Fairly straight forward to do with the horozontal mill on your machine. The tube doubles nicely as a lead screw cover! and it's easy to disconect if need be.
Being able use the quill (in fact the whole machine) manualy is important to me also.
I do have one concern with this idea though..
Do you think the offset distance between the lead screw axis and the quill axis could add some side load or "kick over"? Especialy when the quill is at its fathest travel and "hanging out in mid air"? The ammount of kick (if any) would of course be limited to the fit of the quill and bore so the better we can make the fit in this area the less the possible kick.

Your drive motors sound like a real bargan! Do you know if Babinda01 has any more? I'll have to send him an e-mail and see..

Cheers

Leeroy

[chich2]

Leeroy,
Thanks for the post. Firstly well done on the new spindle idea from the chromed cylinder rod. That should last for ever! You can also buy hydraulic cylinder components like guides and bushes to suit that rod if you did one day encounter some wear. If you go ahead with it I would love to see some pictures if it being made. Feel free to post them on this thread.

I agree with your point of some kick being imposed onto the quill from the screw being mounted out the side but I believe that a close fitting quill and bore should eliminate most if not all of this. In my design I will do everything to make the lead scew as close as possible to the quill. So far the only thing keeping it a distance away is due to the diameter of the large cogged pulley on the leadscrew.

Oh by the way I have forgotten to mention that I have removed the quill lock from the left side of the head and put it in the right side. I had to gently straighten the handle on it to work on the right side and also machine a bit off the end of the cast iron clamp piece to prevent it from protruding out the left side.

I think Babinda01 has 2 motors left but I will more that likely purchase them as spares. You could ask the manufacturer for a quote also. The motors are from Preslite Australia.

Contact for the motors:
Darryl Richards
Sales & Marketing Manager
CPC / Preslite
4-10 Hillwin Street
Reservoir 3073
Victoria
Ph: 039 460 6566
Fx: 039 460 6823
Mb: 0413 774335
Em: [email protected]
Web: www.cpcauto.com.au

The optical encoders are: E2-1000-315 from http://www.usdigital.com/. I also got shielded cable as well. Got em 6 days after I placed the order. They are 8mm bore which will mount straight onto my motor shafts. If you wanted to save some bucks you could just purchase the encoder wheel and the pickup and it may be a bit cheaper. Also if you get an incoder under 1000 counts per rev it's also cheaper. 1000 is a lot when you consider that the encoder wheel consists of 2 bands of 1000 counts 90 Deg out of phase which then gives you 4000 pulses plus direction. That's 0.09 of a degree accuracy on the position of the motor shaft. The encoders are incremental not absolute which means the incremental encoder only counts pulses. If you turn the power off and back on the encoder doesn't know where it left off. It only counts movement. An absolute encoder knows where it is after the power has been turned off and back on. Absolute is way more expensive than incremental. All you have to do with the incremental set up is leave the machine on or simply zero your co-ordinates once you power up each time.

I got back home today from my week away at work so I should be able to do some more on the mill this week.

Cheers
Chich

[macona]

You know, this would be a great time to install a oneshot lube system. Since it will be CNC a motorized one would be even better. It will extend the life of the mill. And since everything is in pieces...

There is one more option for using the Z that you have not mentioned. It is the method that was used on my Supermax. It consists of a 4" ID air cylinder. the rod is removed replaced with the screw attached to the piston. the nut rotates on top of the cylinder on a thrust bearing. A timing pulley is fitted around the nut and is belt driven. Then the screw goes up into the knee. A pressure regulator is then used to adjust the pressure through the bottom port and balances the knee. Mine balances out at around 40 PSI (Guess that meand my knee/table weighs about 500 lbs. When the knee goes up the regualtor keeps it at 40 and when it goes down it dumps to keep it at 40. I think this is the regulator used on mine: http://store.norgren.com/US/en-US/ca...-300-RGLA.html

Seems to work well. I have done some peck routines and it seems pretty responsive. Plus it leaves your head so you can do manual drilling and the like.

[chich2]

macona,
Great post! Yes your system would work perfectly. Nice and lite too. A simple chart could be made up with pressure versus weight on the knee therefore eliminating the worry of heavy jobs and mass..... Good one!

A one shot lube system would be great. I will do a search for home made set ups but do you have any in mind that has details on how it is made?

Chich

[macona]

Bijur (http://www.bijur.com) Is a pretty big name in oiling systems. I hear the parts are pretty cheap. You can get either manual or automatic pumps. These feed into manifolds with flow dividers and then steel lines to your points where you want oil. My mill has a chiba oiler hooked up to the servo power supply so whenever it comes on it starts pumping (Very slowly)Lines are also ran to the nuts to keep them nice and lubed (Well, not on mine anymore, I have ball screws now).

[chich2]

macona,
Thanks for the info. By the way what do you bolkes pay un the US for ball screws. The cheapest ones I can find down under for 18dia X 5mm pitch come in at around $700.00 AU per preload nut assembly and a couple hundred bucks for all the screw.

Chich

[leeroy]

G'day Guys

Thanks for the posts Macona. I think a lube system is a pretty good idea also. On my machine i have those little brass ball bearing oil valves. I think these should easily push out then tap the hole for a bsp pipe fitting. Probably run some 3mm anealed copper tube to a central manafold. If there is nothing comercialy avaliable, shoud be a fairly easy job to make up a small hand driven pump. Just give a few pumps before every job..

As for the air ram on the z axis, man what a great idea!!! :idea: Why didn't we think of that Chich?? I think a single 75mm ram mounted on the side of the knee would be ideal for my machine. Mabe even 2 smaller rams one on each side? There is room at the top of the knee lead screw to mount a pully for drive and plenty of room to mount the drive motor. At 100 psi a 75mm ram would give arround 320 kg of force.
If i can't find a ram at the right price, I think i can make a simple air ram from some extruded alloy tube. Use black delrin (Plastic) for the piston and some "O" ring seals. I have a length of 20mm Dia chrome bar salvaged from an old photo copier for the piston rod. Should be bale to find a supplier in Aus for the regulator valve. I will look into this idea further over the next week and will keep you guys posted..


Cheers

Leeroy

[chich2]

Leeroy,
Yes the air ram idea pushes a very strong argument to automating the knee. In fact there are some industrial machines that use this system of offsetting weight. I have changed my mind and pretty much decided to go ahead with doing the knee over the quill on my my machine as I have plenty of ideas for different configurations on my mill that require the knee to be Z rather than the quill. I have a very acurate air regulator that reacts to very minor pressure variations and a friend of mine is sending a pneumatic cylinder to me for free so a Z knee for me is looking good at this point.

once I have Compleated the CNC Conversion of my HM-52 and done all 4 axis X,Y,Z knee and A, My future plans for my machine at this point are:

1. I will extend the dovetail ram all the way out. Bolted firmly underneath this will be an electric bench grinder. Hey presto! a rigid surface grinder. X axis will sweep backwards and forwards and Y will inch across once per back and forth stroke of X. Z knee will be depth of cut.

2. The HM-52 has a horozontal spindle. In the lathe I will machine a INT30 taper out of a large piece of high tensile stock. I will then place the taper into the horozontal spindle of the HM-52 Mill. I will bolt a turning tool to the table of my Mill and Hey presto! again My mill is now a CNC Lathe! I will turn the piece of stock to a face plate to hold a small 4 Jaw chuck. Sweet! I will then use the macine to CNC turn another INT30 taper which means I can make as many of them as I like. The second taper will go into the spindle and It will be a face plate for a small 3 jaw chuck.

3. Tool changer will be next. The tool changer will be bolted frmly to one end of the mill table pointing up. In this configuration It will be a tool changer for the quill. Standing up on it's edge it will be a tool changer for the horozontal spindle (if it fit's without smashing the other tools into the pillar). It will have a removable head so I can take off all the milling tools and put a head on it that holds turning tools. In this configuration it will look very similar to an industrial CNC lathe tool changer. So that leaves my machine as a very multi use machine. It will be a cnc knee mill, a cnc surface grinder, and a cnc lathe all in one! What a great machine!

[chich2]

Well I'm back home for the week so I have been busy on the backlash quest again. I have stripped down the Milling machine to acsess the Y axis lead screw and nut. Since My mill is pulled apart to do this, the design of this nut has to be such that it can be entirely machined in the lathe. I will go through this photo by photo:

1. The standard y axis nut and a piece of brass stock that I made the new nut from.
2. The stock cleaned up and square.
3. I parted off a chunk. This will be the 2 nut half's
4. Faced the chunks flat and smooth.
5. Both segments bolted together and the mounting pin machined to size.
6. Nut squared up and boared and threaded.
7. and 8. Next was to ensure the surface the nut bolts to on the mill was paralell to the slide. I flipped the Y slide over and milled it flat using the quill and dovetail ram.
9. Made a new retainer washer nice and solid and increased the retainer thread size to M10. You can see how light the standard retainer is.
10. The finished product. The nut comes apart and you shim the 2 halves apart to achieve the correct preload. This can be done on the bench before it is installed and can be easily accessed from under the knee for future adjustment. All that is left to do on the nut is to dowel the 2 segments together.

Chich

[macona]

I would try to use a cylinder co-axial with the leadscrew for the knee. This eliminates potential binding issues i using one or two cylinders elsewhere.

I would seriously rethink the idea of using the mill as a surface grinder. First there is the highly abrasive grinding dust. This WILL get everywhere and it will wear out your machine in no time. Second the x axis of a surface grinder is usually a rack and pinion affair. With the amount of going back and forth you are going to wear out you leadscrews in no time.

If you are really dedicated in needing a surface grinder you could always buid one from scratch. I have seen it done. Dont risk your mill for something like this!

[chich2]

Macona,
Thanks for the concern. I have already designed these problems out by fully shielding the slide ways and containing the dust. The use of coolant almost compleatly eliminates dust as well. Secondly the amount of grinding I will do will be extreemly minimal.
The issue with binding is not that of the screw but however the slides. The HM-52 has a large dovetail slide about 500mm of contact. I assume binding in this area will not be an issue. Once again thanks for the concern but I am going to give it a go.

Chich

[chich2]

Today I started the conversion of my Z axis. I am definately going ahead with converting the knee to cnc over the quill. I need a flat machined surface to bolt the servo mount and air cylinder to so I flipped over the knee and secured it to the machine up side down so I can face it using the dovetail ram. Up until tonight I have the knee in place and locked off square to the collumn. Tommorrow I will re-fit the dovetail ram and vertical spindle assembly and do the job of actually facing the knee.

I won't go through each photo and give a description but if you hold your mouse pointer over the thumbnail it will display the file name of the photo. The file name has a brief description of the photo.

Chich.

[chich2]

Today I replaced the dovetail ram and vertical spindle assembly and bolted it down tight. Following that was another check for square then set up my small boring head to do some facing. The travel on the dovetail ram does not allow me to go any further back towards the column so I set the diameter of the boring as big as I could get it to fit inside the underside of the knee without it hitting any thing. I will either use a mount skinny enough to fit in the gap or carefullt grind and file away the radiused ends of the cut.

I have attached more photo's for you to look at. Once again hover your mouse over the thumbnail to see the file name description.

Chich

[macona]

Yeah, coolant will work to help with the dust. One further note though, the bearings in a bench grinder will not be good enough to get a decent finish with the grinder. Probably best to build your own arbor. Maybe you can belt drive it and run it from your horiz spindle. something like 1:2 ought to get enough speed.

[chich2]

Macona,

[chich2]

Macona,
Thanks for the great info. I have been enquiring about suitable grinding wheels to use as a surface grinder. Eg. Type - Alli oxide, Sillica Carbide, size, grit, recomended speed, suitability to what kind of coolant. Do you know where I could get this type of information? I like your idea of using the horizontal spindle and belt driving a seperate arbor. Good one! Bearing manufactures like SKF and FAG make a ready to go bearing housing with a shaft on 2 bearings preloaded ready to go for this type of application. Normally used on high speed fans and simmilar assemblies this unit would be perfect for the job. Designation "PDN two-bearing housing". You can purchase just the housing by itself and fit 2 deep groove ball bearings and make a shaft to suit OR there is a part number for the complete assemblies.

I'm off back to work for another week so there will be no further progress post's from me until I get back next week,

Chich

[leeroy]

G'day Guys

Well after two weeks of "A bit here and there" the new quill is done.

It was all pretty straight forward as the photos sudgest, with a few exceptions.

Firstly the dia of the chrome bar was 89.995mm as supplied. This was a almost perfect fit on the bore of my mill head(90.005mm).
However i had a feeling it might expand slightly when i drilled the center out. Which it did by almost 0.03mm!!! There must have been some residual stresses in the steel which i "releaved" when i drilled it out. This ment some honing of the bore was required to get the fit right, which was done with an automotive cilinder hone in a cordless drill.

Secondly, Hard chrome plated bar is REALLY FRIKIN HARD!!
When i went to cut the rack teeth, HSS hardly left a mark on it let alone cut it! I had to resort to using a few old solid carbide end mills, reground to a "v" shape. One roughing tool ground slightly undersize, held in the collet chuck and used in the conventional way, and another form tool carfully ground to fit the original teeth and held in my boring head. I also marked the teeth positions and using a 4" angle grinder, ground the some of the chrome away in each tooth position. This gave the cutter tip much better life.

The finial result is even better than expected. Due to the top end being about 0.005 larger than the rest (Mostly due to the interference fit of the top bearing) the quill actualy gets slightly tighter as it is lowered, just what i needed!

The name if each pic is a shot description.

Cheers

Leeroy

[macona]

Nice work on the quill!

As for grinding wheel types I am not sure. I have never done surface grinding.

As for the spindle I think you are going to want something with anguar contac bearing. Even deep groove bearings still have some annular play. I tried deep groove on a lttle tool post frinder I made oce and coulnt get a finish worth a darn.

Maybe of you got one of those spindle housings and installed angular contact you could do it, though you are going to need an arbor that has a not to preload the bearings.

[macona]

Oh yeah, ask over at www.practicalmachinist.com for info on wheel selection.