[ger21]

I'm a bit confused by an earlier post. If I used my mini-mill motor and spindle for my gantry machine, why would'nt it be fast enough? I should think if it's fast enough for the mini-mill in the first place why then is it not fast enough for my gantry? I have cut both plastic and aluminum with my mini-mill and never had a problem, so again why not fast? I need to know if I can use the motor with a step pulley to achive usable speeds. How do I calculate pulley diameters? :idea:

What do you want to cut? You said you want a 30,000 rpm spindle, but it was mentioned that the LMS spindle is only good for 5,000 rpm. If your cutting wood, you'll usually want between 10,000 to 20,000.

What's wrong with a variable speed router? You'll most likely have to spend quite a bit more money to get comparable performance.

[SPEEDRE]

Yep going to use variable speed router. It's the best idea short of having a production model expensive item. I hope I did'nt cause any trouble. Dremel is not an option too much runout and Z slop. The next problem dust conrtol. See my posts on this subject. Over and out..

[eqreservoir]

Here is an idea for a spindle I found on the Internet which might be of interest. http://www.rcmodels.net/cnc/hobby/size/home2.html

HTj

[chuckknigh]

Harbor Freight and Homier both carry a cheap pneumatic grinder, which appears very similar in structure to a belt driven spindle. I've had the idea, for a while, to buy one of them and retrofit it using the existing shaft/chuck, and hook up a pulley in place of the impeller. It'd definitely need new bearings, but that probably would be no harder than finding some metric bearings, since it's Chinese.

I wonder if anyone has tried something like this?

-- Chuck Knight

[MikeAber]

If there is any interest in making your own spindle check out http://www.vxb.com
for angular contact spindle ball bearings starting @ $10.00 a pair rated at 27,000 RPM.
They also have double row angular contact ball bearings in 12mm and 15mm sizes (good for ball screw 5/8" & 3/4" conversions) for $10.00 each

[signIT]

Hi,

I have built a spindle like that MikeAber refer to in a link, a aluminium tube with two simple rubber sealing ballbearing and a 8 mm axle I run this spindle with a model DC motor ~8V and ~5A just 40W, I dont know the exactly rpm but I think it is ~10000 rpm, the problem is it runs very hot I can't hardly touch the aluminum tube my question is why, should I change to ordinary ballbearings without sealing?

Leffe

[signIT]

Here is an idea for a spindle I found on the Internet which might be of interest. http://www.rcmodels.net/cnc/hobby/size/home2.html

HTj

This rcmodel spindle runs at 30000rpm, how can one run a router at this high speed without burning wood and is it a magic spindle rpm together with the speed move with Z and Y axle.

I will route som Ash can I take light cuts with 5000rpm and say 30mm/second without burning? or do I need very high spindle speed like 30000rpm.

I use a 6mm two flute HSS end mill, I can see that a high spindle speed and low ~10mm x,y movement will burn the Ash.

Is there a calculator that can create the right condition if so where,

Leffe

[ger21]

Is there a calculator that can create the right condition if so where,

Leffe

Most tool manufacturers will provide speed and feed information for their tooling. Check out http://www.onsrud.com Download their catalogs, all the info is in the back.

5000 RPM is a bit slow for wood. Too slow and the bit will want to grab the wood instead of cut it.

[PEU]

Im also in the search of a decent spindle/router for my project, links in the cnczone are welcome .

I found this page today: Spindle design

thanks


Pablo

[MikeAber]

The "skateboard" bearings so popular in hobby spindles (8mm inside diameter) are in most cases a deep groove ball bearing designed to support moderate axial loads and heavy radial loads. When you put a heavy axial load on them due to cutting or preload they will overheat as all of the load (friction) is located on a small contact area.

The small hand held, low cost spindles (Dremel, routers, rotary tools, and die grinders use these bearings without preloading and are usually a slip fit on the spindle shaft "sloppy". Limiting runout in a tool designed to be held in your hands or on a wheel attached to a skate or skateboard is not required.

No preload = no friction. High speed operation without a load -- no problem -- runout -- sloppy

Angular contact single row ball bearings are designed for heavy axial and radial loads in one of two axial load directions. Typically you would use two of these in a simple spindle in an arrangement similar to the wheel bearings on the front axle spindles of an auto. These bearings are usually press-fit into the spindle housing and require preload to eliminate runout. Too much preload, workload, rpm or mis-allignment or lack of lubrication would make the bearings run hot. Try to run a front wheel spindle at 10,000 rpm and see how hot it will get.

Low rpm spindles such as drill presses, drill/mills, mini mills, and lathes use this type of bearing up to about a 5,000 rpm limit if a quality bearing is used with adequate lubrication and light preload. Heavy preload would decrease the rpm limit due to increased friction (heat) and keep spindle runout under control during heavy loads.

Angular contact double row ball bearings are a pre-loaded pair of angular contact bearings that handle axial and radial loads well. Higher quality spindles will use these to achieve higher rpm. These bearings will usually be press-fit onto the spindle shaft at the business end of things and a "premium grade" angular or radial ball bearing on the non-business end. The bearings are usually press-fit into the spindle housing with an end cap in place to prevent movement in the housing due to axial thrust forces.

Want more rpms? --- Pay more money for precision bearings that are designed to do the job.

There are no cheap, high speed, quality spindles because quality is not cheap.

If you want a quality spindle pay the price for one in one way or another.
Learn the skills necessary to make your own or purchase a quality product to obtain quality results.

[MikeAber]

H500

You could try this,

Clean the housing inside where the bearing is and remove the foam rubber then oil the bearing, shaft and housing. Mix some epoxy putty (Home Depot) and place into the housing area that holds the bearing in both halves (just enough to fill the area when the bearing is inserted or a little less) then reassemble. The oil will prevent the epoxy from sticking to anything.

[MikeAber]

Speedre

The mini-mill head assembly with motor weighs over 30 pounds!

Can your gantry Z axis support that much weight?
This is not a bad idea if your machine can handle the weight.
What is your target rpm for the mini-mill spindle to operate at?
Pulley ratios are easy: v or flat belts 1"---2" = 2:1 or 1:2
timing belt 20 tooth --- 10 tooth = 1:2 or 2:1

I have a mini-mill spindle housing and I am also researching the possibility of using it on my gantry mill. My maximum target rpm is 5,000-6,000 rpm. I believe this is possible if the bearing preload is reduced along with a synthetic high speed grease and light cuts. I am also looking for a set of higher quality spindle bearings.

The new mini-mill spindle I have is very tight. I measured the runout at .0001".

[signIT]

Puh! a lesson in why and how, now I understand the problem with my low tech design and the heat that will occur.

One of the ISEL UFM-500 spindle motor with collets up to 6mm may be a nice buy they will cost around $250.

Just wondering about the bearing and runout http://www.unimatic.co.uk/education/...motor-w500.asp

Leffe

[toolmkr13]

Hello;
I'm new to the forum but have been in the machine trades for 30 years. I've found that SHERLINE sells a spindle cartradge for their mini mill that is a possibility. Per info on their site, one must adjust for a little more endplay (0003-0005) to get 10,000 rpm. I was looking at the HARBOR FREIGHT catalog that came with an order yesterday and they have a 1/4 shank pneumatic die grinder for $9.99. The bearings are good for 22,000 rpm. I'm thinking of disecting and removing the vanes and attaching a cog pulley to the top of the shaft. A 1/10th HP. 3450 rpm motor and the correct pulley diameters should give the needed spindle speed and power for wood. What do you think?

Tony

[MikeAber]

Hi Leffe,

Thanks for the link to that spindle. It looks like it is designed for serious business. I really like the 1050 watt spindle for my uses. I notice the spindle nose bearing housing is massive.

I think you are onto something good there.

Mike

[MikeAber]

Hi Tony,

I think your idea will work as long as you keep oiling the bearings with air tool oil.
I do not believe you will be happy with 1/10 horsepower.

The SHERLINE spindle is a well engineered quality product for light duty high speed use. It is amazing what it can do at lower spindle speeds.

Mike

[toolmkr13]

Mike;
You are right about lower spindle speeds. I've cut many, many profiles in some very difficult plastices with .017 diam, cutters on a mill that maxxed out at 6000 rpm on the spindle. A lot of the seceret to cutting is not running the cutter at MACH ONE, but rather getting the load per tooth of the cutter correct and getting the chips out of the way.

Tony

[gcz]

i've been following this thread about spindles and googling all over to learn about it myself.
what i seem to get is that the worst problem will be heat induced elongation of the shaft and consequent excessive loading of the bearings.
? - if the spindle chassis and the shaft are made of identical material, will this not obviate the problem entirely?
? - if each end of the spindle is in a roller bearing only, and a thin disk on the lower end of the shaft is captured between thrust bearings, then will not the thin-ness of the disk obviate any problem of elongation just simply because it's not very long?

obviously the smaller the diameter of the shaft, the faster it will max because the bearing travel will be proportionately shorter each rev than on larger diameter.

these look like good clues to start making a test spindle - anybody see flaws or something i overlook?

[H500]

H500
You could try this,

Clean the housing inside where the bearing is and remove the foam rubber then oil the bearing, shaft and housing. Mix some epoxy putty (Home Depot) and place into the housing area that holds the bearing in both halves (just enough to fill the area when the bearing is inserted or a little less) then reassemble. The oil will prevent the epoxy from sticking to anything.

Mike, thanks for the suggestion. I might try wrapping the parts in Saran wrap and doing it half at a time, so that it can still be disassembled.

[MikeAber]

Mike;
You are right about lower spindle speeds. I've cut many, many profiles in some very difficult plastices with .017 diam, cutters on a mill that maxxed out at 6000 rpm on the spindle. A lot of the seceret to cutting is not running the cutter at MACH ONE, but rather getting the load per tooth of the cutter correct and getting the chips out of the way.

Tony

I agree with you completely. Learn how to make chips not dust.

Mike