[dwalsh62]

Hi Dale, the ISO15 spindle looks very good, but I'm wondering if you can do more than engraving with it. The largest shank size is about 1/4" right? Can you talk about what kinds of work this spindle is good for? I'm not dissing your spindle, but trying to figure out where it fits.

I am a hobbyist, and am planning my first mill. I would use the spindle for some steel, but more aluminum, and some deep 3D work in wood (up to 6" deep). For some of it I think I would need at least a 1/2" shank. Would ISO20 be a better fit for me? The ISO15 is in budget, the ISO30 is not.

-Steve

ER16 will hold up to 3/8 tooling.

One word of advise, don't let your budget determine your requirements, determine your requirements and then work it into your budget.

I've cut tool steel without any issues using a 10mm 4-flute end mill at depths of 0.200in (5.08mm) and the motor you power it with is just as important as the spindle is, a small motor may not have the power required to keep the tool turning when cutting hard material and more power means more money and explains why real spindle motors cost over $3000.00 (I'm working on a reasonably priced solution).

Working strictly based on a small budget and you will make many sacrifices in your machine design so plan well, decide what your minimum acceptable requirements will be and do not go below them.

Making a larger VMC and using BT15/ISO15 may not be in your best interests unless you're making jewelry so I suggest you plan your machine size accordingly.

A work area of 16.5in x 9.25in or 24in x 6in are a suitable size for BT15/ISO15 or BT20/ISO20 and the 16.5in x 9.25in tables are available for about $300,00 with 1/2in T-Slots and are suitable for 20mm linear rails which aren't too expensive.

If you want to use 1/2in tooling then I suggest BT20/ISO20 (at a minimum) or BT30/ISO30 (recommended) but these will cost you more and you should budget accordingly.

You can make a fairly rigid small VMC frame using 4in x 8in x 35in (1/2in wall thickness) rectangular tubing and 12in x 4in (1/2in thick) channel for the base and 1in x 2in cold rolled for rail seats for about $300.00 in material and about another $175.00 for the material to make the XY carriage leaving you only the Z head and table to figure out and will weigh in around 500-800 lbs when the frame is assembled (not fully assembled machine weight), my Z head assembly's average weight is around 250lbs with spindle motor attached for a machine of this size and since I add a 6in x 1/2in thick skirt to the channel base and weld in some webbing for added rigidity my frame weight before servos is around 1000 lbs.

Going to an 8in x 8in x 35in (1/2in wall) square tubing will increase rigidity well beyond the needs and you can get away with a 3in x 7in x 35in (1/2in wall) rectangular tubing and still have good rigidity if you design it well.

Those round column mills you see have a 5in or 6in round column with 3/8 wall thickness (depending on the make/model) and they're fairly rigid but the head will shift on the column if it is not keyed and most aren't.

I personally dislike round columns and dovetail on small machines, dovetail machines are the greatest waste of table size vs table travel - 30in long table has 20in of Y travel, linear rail carriage designs allow for greater than 100% table travel and the carriage is roughly about 1.5 times the length of the table so the footprint is smaller for the same size of table travels so plan your machine well.

If your thinking about aluminum extrusion or 8020 material as a frame then rigidity isn't a priority and precision is pretty much non-existent as well as machining hard materials.

Another thing I recommend, since your going to buy ballscrews for your machine build, buy DFU1605 or DFU2005 and not SFU1605 or SFU2005, the double length nut will handle the required loads of a milling machine and last significantly longer.

If you can't afford $1200.00 for a real CNC panel then a breakout board and Mach3 or EMC2 is something you can consider but realize, software based solution are not really cheap if your looking to get any real precision out of it, especially using stepper motors, this brings you back to your budget, plan accordingly.

I use only servo motors in a VMC, you can get a set of 60mm 4/5 HP servos and drivers for around $1500.00 shipped or a set of 90mm 1.5HP servos and drivers for $1900.00 shipped.

1600Oz Nema 34 Stepper motors cost around $130.00 shipped form china, add a suitable driver and power supply for another $150.00 looks great on paper but, 1600Oz only occurs below 50RPM and despite what they claim, power drops as RPM increases so you wont have sufficient power at 1000RPM and you'll never see 2000RPM out of a stepper before it stalls trying to move your axis so your $800.00 stepper kit while looks like a saving, has actually cost you performance and precision.

This is why it is common to see a 4:1 (or higher ratio) belt pulley setup with stepper motors to increase available power and sacrifice rapids to 80in per min and maximum feedrate to 25in per min.

Lastly, if your budget is really small (less than $1500.00, forego making a machine and buy one that is within your budget, you may not get what you want but you will get something, in most instances these machines are not suitable for CNC conversion since the mass/rigity is not there and the hardware (like lead screws) is just not suitable and the cost of conversion adds up quickly.

If you've never owned a CNC mill, I suggest you might want to start off with a sherline or similar so you can get a feel for it before you dump a wheel-barrow full of pennies on a machine or build, I've seen it many times, people ask me to build them a frame and I do, then it sits for years unfinished because they didn't realize that this is an expensive hobby to be in or that to get what they want isn't as cheap as they thought it would be.

I am trying to provide affordable solutions for things like spindles but there is no way to make the $350.00 ATC spindle that everybody wants unless I can do quantities of 10,000 and I don't have the funds to do this or 10,000 people beating my door in to get one and pay in advance.

Even if you managed to make a shaft for your own spindle conversion, heat treating will run about $160.00 for the one shaft because you need to temper and harden and then grinding will cost you at least $250.00 due to setup and time if you don't know someone with a bore grinder who will do you a favor on the cheap and these are just some of the hidden costs that are never explained.

Making things in quantity helps lower costs, I can heat treat 10 shaft lots for $400.00 a lot so this breaks down to $40.00 a shaft and $40.00 sounds great but I have to do 10 shafts which means I need to sell at least 10 spindles to be able to get this price so I can sell at the low price I do.

AC bearings are another expensive thing in spindles, high quality precision AC spindle bearings cost $350.00 a pair (matched set) if I buy 200 pairs direct from the manufacturer, if I buy 1-3 pairs then the cost is about $250.00 each, luckily we use this size for some HAAS and other manufacturers shafts so I can bump up the quantity 50 pairs and pay a little less than $300.00 a pair.

Everybody wants a low price and they want to wait for the low price before they buy and the reality of it is this, if they want a low price then they have to buy now, by increasing production volume I can lower the price, if waiting for that lower price is your game then you'll never get one at the price you want and it has been decided that only those who buy on kickstarter will get the lowest price, if funding is exceeded then they will receive a partial refund based on the production cost savings, those who purchase later will pay more than the kickstarter advertised price as one of the guys in our group will be matching the kickstarter funding so he can have stock on hand for those who wish to purchase later and he will expect a profit on his investment and rightly so deserved.

[steve123]

Thanks for your very informative reply. It will be at least 8 months before I need the spindle. I will budget for a good one. It will probably be ISO20. I see that you are working very hard on this project, and I wish you well. If you are curious, my evolving granite bed gantry mill design is at http://www.cnczone.com/forums/vertic...ry_mill-2.html

[handlewanker]

Hi Dale, coming from where you're at, you've hit the nail squarely on the head......if you're in the market for a spindle subscribing to the Kickstarter program guarantees you get the very best price and I could not imagine why anyone would want to wait.

BTW, you forgot to mention the steak knives for the first 100 buyers.....LOL.

In your last post you refer to the heavy wall square tube mill frame build as a DIY mill build method......David DeCaussin uses this method in his UMC 10 mill build with great success.

BTW again, if you remove the drive dogs on the end of the spindle for an ATC solution with ISO 30 tools, you stand the risk of the tool, without drive dogs, turning in the taper and destroying the taper seating in the spindle.

One method I think will work with this problem is to have the ISO 30 tools ......without the slotted collar..... which is only used in manual tool changes if the drive dogs are in the spindle, and have instead the collar milled/ground away to leave a single drive peg instead of the collar with two slots.

This would work with new tools when they are being made in the soft state as no drive collar needs to be made, and the drive peg could be a screwed insert, so saving on the material which has to be of a large diam to get the collar as part of the ISO 30 design.

For existing tools with hardened and ground geometry, the collar could be cut off with water jet or ground off whichever is the cheapest without affecting the hardness of the tool or distorting it by heat.

This is only a thought, but the prospect of a tool destroying the integrity of the spindle taper when it turns is not something you'd want to have when you're chasing tenths for spindle/tooling run out.

When the tools are in the table rack the spindle is lowered onto the ISO 30 tool shank and 10 to 1 the drive dog on the spindle will be in the empty space that was the collar......and if the spindle slowly rotates it will come round and butt against the drive dog that is on the tool (collar) and so you have a positive drive, no possibility of the tool turning in the taper when the tool is finally drawn up by the draw bar.

Another solution would be to have a single spring loaded pin in place of the spindle drive dogs, that would drop into the slot in the tool collar when the spindle is initially rotated before clamping the tool.......the tool being restrained from turning in the rack so that the spring loaded pin could "find" the slot in the ISO 30 collar as it turned.....which means the standard tools with slotted collar could be used without modification, which is a much cheaper and simpler solution DIY wise.
Ian.

[dwalsh62]

Yes, I'm not the first to use thick-walled tubes, I have personally had discussions with David regarding the 6in x 8in thick-wall tube column design/implementation in the UMC 10 and he tells me he's made a couple for some friends using 5in x 7in thick-wall tubing with equally good results.

I have collobrated on some autocad drawings with David to get designs that exceeds most requirements using the 5in x 7in, 4in x 8in and 6in x 8in tubing sizes and have successfully made several small VMC frames that have excellent properties but my preference seems to be the 5in x 7in due to the larger depth than the 4in x 8in and the fact that David has used it successfully as a column with a length of 37in is a sign it's a suitable size.

David originally cast the rail seats (cast steel not cast iron) onto the UMC 10 column using a couple of cherry buds to heat the metal tube to almost a molten state where the rails seats were to be cast, in another build he arc-welded the rail seats to save money and time but spent more time machining the rail seats true due to warp-age from welding but got a much nicer looking finish after he scalloped for stress relief.

I currently TIG mine for minimum warp-age (costs a little more to do) and requires less machining to true them up but the welds dont look as pretty as ARC or MIG becuase the two later welding processes put excessive material down which you can machine a nice chamfer into.

With TIG it's harder to put as much filler to obtain the same results unless you have a lot of time and can go over it many times building it up so I'm in the market for a suitable MIG to aid in framing, lot's of used Millers around for less than $750.00 so I'l probably snag one of them.

OK, enough about frames, back to spindles.

A BT30 (8K RPM) spindle has 1400lbs of pulling force and 1960lbs of seat pressure, it is unlikely a tool will slip as the required force to slip is greater than the cutting force of pretty much most materials.

Sadly enough, while everyone shows ratings of 3000N (680 lbs) for a BT20/ISO20 drawbar, ALL MANUFACTURERS only use 1700N (380 lbs) in BT20/ISO20 spindles so if you really want that 3000N (680 lbs) force, you're looking at a custom or specialty BT20/ISO20 spindle and this will be expensive.

Originally the taper would be harder than the tool holder (TAPER = HRC 52-58 / ToolHolder = HRC 40-42) because tool holders are considered consumable however, with dogs, manufacturers found they could save money on hardening, tempering and grinding so the majority (self included) do them at HRC 40-42 like the tool holders and only BT50/CAT50 are nose quenched at HRC 52-56 while the rest of the shaft is only T295 tempered.

Also, despite popular belief, shafts are not coated or plated with anything, 40Cr, 42Cr, 4140, 4150 and a cast steel alloy with molybdenum and nickel (HAAS uses this cast steel in their 40 and 50 size shafts) are the common shaft materials and these are fairly rust resistant.

Jogging the spindle shouldn't create any wear or damage to the taper, the taper wouldn't be in contact with the tool holder at this point as it still has to move down a 3/8in (10mm) minimum for contact and it shouldn't be turning fast to find the slots (10-15 RPM if you can't jog your spindle), shorter dogs with spring loaded pins could be used for alignment or you could use spindle orientation and always insert/eject in the same oriented position by using a spindle motor with an encoder (or an encoder on the spindle itself) and a closed loop Inverter/VFD.

There are many ways to skin a cat, some are more expensive than others but there are options to fit every budget and it all boils down to planning.

[vertcnc]

On the machine based made from tube, is the colum welded to the base? Or is a flange welded to the colum, then bolted to the base. Is the colum tube slotted for the ballnut connection to the head? Are there any drawings available?

[dwalsh62]

When I fabricate a frame the column is never welded to the base.

I attached a basic drawings for a column that shows a 5in x 7in tube with a wider base, I make this wider section out of pieces and weld them to the tube (like a tongue and groove) and then grind the welds flat.

The rail seats are 1in x 2in cold rolled bar stock that are welded onto the tube (length of seats determined by travel) and the BK20 blocks sit between the rail seats.

This thread really isn't the place to discuss building your frame.

Attached a second drawing if more rigidity is required

[vertcnc]

Dale,

Thanks for the drawing and information. I looking into possibly building the frame. I will start a new thread.

[arachid1978]

does any body have cad file for iso30 scm cone?

[arachid1978]

does any body have dwg or cad file of iso30 scm cone?

[andypugh]

does any body have dwg or cad file of iso30 scm cone?

Does this page help?

Machine Tool Shanks (Tapers)

[arachid1978]

very nice page but don't have iso30 for scm machine.

[andypugh]

very nice page but don't have iso30 for scm machine.

You need the toothed flange?
UCHWYTY DO CNC ISO 30 Z?BATA FLANSZA do maszyny takich jak Scm, Morbidelli, Record, Masterwood
Might get you close, but no toothing details.

[Azalin]

Sorry for the funny question especially if its mentioned before. How the balls doesn't fall when there is no pull stud gripped?

[digits]

Sorry for the funny question especially if its mentioned before. How the balls doesn't fall when there is no pull stud gripped?

They are physically too large to fall out of the holes in the gripper body.