Construction of a hobby HMC-Spindle Horsepower

I'm about halfway through the design phase of a hobby HMC for my home garage. I've built a VMC and it worked well in the 1HP spindle class, would do everything a Bridgeport would do as far as cutting power. This time, I'm going for a Horizontal.

It's a linear rail based machine, on an steel skeleton frame that's encased in polymer concrete. The base casting that will hold the Z and Y axes will weigh in around 1300lbs. The Vertical X axis will weigh around 450lbs. (weights are estimates based on volume and solid models)

The spindle is a Chinese import BT30 spindle, which is surprisingly well machined and hardened. I was anticipating a rough part but really it's a bargain for what I got. The bearings in it may wear out in a year but they are standard sizes and are P4 grade...well...marked as P4 grade. I did throw all the cap screws out and cleaned and retapped all the blind holes, and replaced all the cap screws. Spindle runout was measured with a nice little 0.0001" resolution indicator and barely twitched the needle on four contact points inside the taper. I'm a bit concerned about bearing protection, but they do have a labyrinth style seal protecting them in the front.

The linear rails are 4-point contact 25mm section width-same as the Haas Toolroom mills. They're Hiwin brand, and are "medium" preload. The rails at hand will allow for a 12"x12"x15" work envelope.

The spindle is driven by a 5M-HTD style belt, two belts 20mm wide.

What kind of horsepower spindle motor do I need to be looking for? The spindle is rated for 6000RPM continuous operation. I'm thinking 1 or 2HP would be enough, but if a machine this size with a 5MHTD needs a 3HP motor to play the game, well, I'll make the spindle mount big enough to handle it.

It's not in the class of a Speedio for sure, but it will do for garage work. Hopefully it'll do for a little paying work, until I can afford to buy a Kitamura or a Brother one day!

This might be a better discussion for over at the zone, but it sounds like you're making about a 2000lb machine, and you might be able to get some professional work done with it. Hiwin makes perfectly fine linear rails, as long as they're genuine and not knockoffs. There are a lot of knockoffs. I'd want more than 6000rpm in any event. I'd probably aim for 3hp if it was me. Better to have and not need than need and not have. But, whatever you do, put a tool changer on it. I'd rather have a 1hp machine with a ATC than a 10hp machine without one.

I started my own shop back in the mid 80`s and soon started playing with old NC and CNC mills and well I had a lot of fun with them the best thing I ever did was take the jump and buy a "NEW" Fadal and stopped screwing around with the machines and started making parts and MONEY...

I had no idea how much time I was spending screwing around and not making money tell I got a real machine and soon found out I could easily clear 1K a day off a 60K machine ,,,

The point I am trying to make is if your playing with machines to have fun that's great ,, but if your end game is to mnake money your wasting a ton of time ,, I learned that the hard way ,

Wolfram Malukker said:

I'm about halfway through the design phase of a hobby HMC for my home garage. I've built a VMC and it worked well in the 1HP spindle class, would do everything a Bridgeport would do as far as cutting power. This time, I'm going for a Horizontal.

It's a linear rail based machine, on an steel skeleton frame that's encased in polymer concrete. The base casting that will hold the Z and Y axes will weigh in around 1300lbs. The Vertical X axis will weigh around 450lbs. (weights are estimates based on volume and solid models)

The spindle is a Chinese import BT30 spindle, which is surprisingly well machined and hardened. I was anticipating a rough part but really it's a bargain for what I got. The bearings in it may wear out in a year but they are standard sizes and are P4 grade...well...marked as P4 grade. I did throw all the cap screws out and cleaned and retapped all the blind holes, and replaced all the cap screws. Spindle runout was measured with a nice little 0.0001" resolution indicator and barely twitched the needle on four contact points inside the taper. I'm a bit concerned about bearing protection, but they do have a labyrinth style seal protecting them in the front.

The linear rails are 4-point contact 25mm section width-same as the Haas Toolroom mills. They're Hiwin brand, and are "medium" preload. The rails at hand will allow for a 12"x12"x15" work envelope.

The spindle is driven by a 5M-HTD style belt, two belts 20mm wide.

What kind of horsepower spindle motor do I need to be looking for? The spindle is rated for 6000RPM continuous operation. I'm thinking 1 or 2HP would be enough, but if a machine this size with a 5MHTD needs a 3HP motor to play the game, well, I'll make the spindle mount big enough to handle it.

It's not in the class of a Speedio for sure, but it will do for garage work. Hopefully it'll do for a little paying work, until I can afford to buy a Kitamura or a Brother one day!

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Actually that doesn't sound so bad, everything you have sketched out seems in balance with a Tormach 1100 MX etc. IF someone scaled it up with an additional 650 lbs.

So 3 HP would be right on. (current Tormach MX 1100 is 2HP.).

Potentially the concept for your horizontal could yield a pretty accurate and precise machine that could have pretty decent surface finishes.

Spindles don't scale proportionately so a smaller machine needs a physically larger spindle head stock and assembly. (seems you get that). That's why a new type of horizontal might work better. [for a smaller machine ].

If you check out Robrenz you tube channel and Macroreps they both have good stuff about modifying "Chinese" equipment, i.e. pull it apart and fix things that are not what they might or should be (especially spindles), tool maker style. + the German guy (TKTK - who's name I've blanked on - for shame shame, will dig up in a mo STEFAN GOTTESWINTER lol <--- Stuff he does is text book and beyond , very clever, cool gizer, his actual day job is machining / toolmaker high level skilled German "Peep" . ) - pulls apart Chinese chucks and mills and re-scrapes stuff and laps etc.for his home shop. He has some good hacks to make lesser equipment more precise and reliable.

Also there a few guys on youtube that have done pretty decent Epoxy "Granite" composite mills - it's a god awful mess to do but seems what they finish up with is pretty decent. Very time consuming for building just one for the first time.

If the basic travels are lessened and the work envelope is made proportionally smaller it is possible to have a small force loop that is somewhat proportionately more rigid. That seems to be the failure of some/most "Hobby" machines, work envelope is wildly too large compared to the lack of rigidity of the machine.

What's the work envelope maybe / travels ? 12"x12"x15" ? Hmmmm

There is a market for US home grown garage / heavy "benchtop" machine that's precise.

Higher RPM spindle might not go a amiss either depending on your goals. Sometimes I wish machines had spindles you could swap out from lower RPM higher torque to go to 30K rpm or 40K rpm but seems some air spindle attachments get some traction for engraving like tasks. A "benchtop" horizontal might allow you to do that (layout / accessibility wise).

Horses for courses and depending on actual goals might be worth while ?

But as D.D.Machine says Time is valuable.

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@Wolfram Malukker if you want something like a Horizontal in a vertical there are a number of Makino PS 65s and 95s second hand (floating around) that actually have a spindle "based" on one of their horizontal machines a51 -ish ... 40 HP - a lot of power through the range. But might not fit in your garage ? / financing ? If you are into horizontals and high torque cuts in difficult materials. Accurate.

D.D.Machine said:

I started my own shop back in the mid 80`s and soon started playing with old NC and CNC mills and well I had a lot of fun with them the best thing I ever did was take the jump and buy a "NEW" Fadal and stopped screwing around with the machines and started making parts and MONEY...

I had no idea how much time I was spending screwing around and not making money tell I got a real machine and soon found out I could easily clear 1K a day off a 60K machine ,,,

The point I am trying to make is if your playing with machines to have fun that's great ,, but if your end game is to mnake money your wasting a ton of time ,, I learned that the hard way ,

Click to expand...

I'm quite clear on that-If I had the electrical hookup and *permanant* concrete floored shop to put one in, I'd plonk a 25K$ used VMC down and dive in. Unfortunately, I don't have that right now. I've got a 1-car garage with a rough-cast 5" thick reinforced slab and 30A/220V 1 phase service.

When I built my first one, it was an epoxy column bolted to a steel plate table base. It worked OK but had to run slow and avoid certain feeds/speeds in steel or it'd set the whole table wailin' dancin' across the floor if you hit a resonance. Base too light!

Right now, my "machine shop" is a result of COVID knocking me out of my day job working at a CNC job shop. I was tasked with all the jobs that the real operators got laid off from because our parent corporation decided we didn't need people to make even higher profits, and then when the big scare of COVID killing off our customers came, they laid off even more...and I got the cut.

I have a few small customers who send three or four jobs a week doing onesy-twosy stuff, I do the CAD/prints and then job out anything that isn't manual lathe or welding/fab work. As of today, that became official...I did not get recalled to my day job before the return-to-work cutoff.

If this onesy-twosey stuff can convert to regular work, I'll make the jump again to owning my own shop-I had a hot rod/street rod shop for 5 years, and enjoyed it all the way up to the "business" part of the business. I'll definitely hire an accountant to take those headaches out this time. IF/When that happens, You better believe I'll be looking at a recent, used, "real" machine to put the chips in the bucket!

If it doesn't, well, then building a home-shop horizontal and getting good semi-pro performance out of it is something that can follow me to work at my next job too. I've got a possible contract drafting job lined up right now, that'll get me 6-months down the road and we'll see if I'm lining up at the used machinery sales auction then.

Cameraman, the work envelope would be 12x12x15 MAX. That's the total travel available using the rails I bought a few years ago thinking I was going to do a bridge-style fixed gantry machine for routing out plate work, stuff that really is better suited for waterjet/lasercut.

That 12x12x15 envelope would be if there was no tombstone or angle plate fitted, and the 15" is in the Z-direction so some of that 15" gets chewed up in tooling length. That said, the BT30 spindle probably doesn't wanna do much work with the tool hangin' out 3" unless all I'm doing is drilling or boring. I have had enough trouble with 40 taper stuff and stickouts more than 4"!

I came for Digger Doug

Forget it. Buy a Swiss-Mak.

Just so we're clear, there are plenty of professional machines that you could power from 220v/30a and 5" of reinforced concrete is fine for nearly any small professional machine. You might need to tweak your spindle accel/decel but you're building machines from scratch so that's definitely not beyond you.

If you want to build something, build something. If you want to make parts buy a machine and make parts.

you can run a mini mill off a 30 amp breaker ,,,

Comatose said:

Just so we're clear, there are plenty of professional machines that you could power from 220v/30a and 5" of reinforced concrete is fine for nearly any small professional machine. You might need to tweak your spindle accel/decel but you're building machines from scratch so that's definitely not beyond you.

If you want to build something, build something. If you want to make parts buy a machine and make parts.

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To clarify, that's 220/30A single phase.

If there are still a few small machines that fit inside that box, I'll definitely look into them-if I can get a small mill in the shop faster for affordable money it would go a long way to making this thing work.

That said, I do know where a 1995 Mazak Quick-Turn 15N is sitting...turret rebuilt, spindle rebuilt but still in a box missing the spindle bearings. We sent the spindle in for a quote, they quoted and the management didn't get back to them...by the time they got back with Mazak the spindle grinding work was completely done and they were minutes from fitting the bearings! It's a T32-2 Mazatrol and basically we got told if anything electronic died we were out of luck to repair it, so it's all still sitting in the storage shed. Unfortunately, even that machine is too large to fit in the box.

Right now, I'm going to move forward building this one as a minor-leagues level machine. Tormach class, I guess you'd call it.

I'm looking at a 2HP servo for the spindle, but can't find any that do more than about 3000RPM. That would work out OK with the spindle being limited to 6000RPM though, with a 2:1 stepup drive. I've already got a 1.25HP Yaskawa servo, but it's an old one and I can't find the matching drive these days.

I think most people figure out it's a hell of a lot smarter to invest in the infrastructure to support real machines instead of screwing around with garbage.

You're committing a ton of time and resources to this and for what? A pile of parts that will never pay you back and is worth nothing to sell.

Wolfram Malukker said:

To clarify, that's 220/30A single phase.......

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Mori Seiki TV30 will run on that without even needing a roto-phase or other phase converter. Only thing needed is a .75kw inverter for the coolant pump motor. Or a single phase coolant pump. I did mine with the inverter as that was cheaper than a single phase pump.

This forum is not geared toward home brewed hobby mills. You'd be in a more accommodating crowd over at CNC Zone.