Hiteco 4hp spindle with .006 runout

Hello all, I am looking for your thoughts or advice. I purchased the 4hp in November of last year. Avid responded very quickly after I sent documentation of the problem, here is part of the response:

Hello Brian,

Thank you for your patience. I spoke with the team and we were able to find a 4 HP spindle that has not been used but was unpackaged. It has been tested and is perfectly functional. The original price for a 4 HP spindle is $1,295 and the discounted price is $1,045. We looked into the spindle repair option with Hiteco and due to the nature of the damage and the additional cost of the shipping fees, we determined that a replacement spindle is the more cost effective and quicker solution. Please let us know if you would like to go ahead with this offer, payment can be made over the phone with card or we can email a PayPal request. Let us know you preference. We will keep an eye out for your update and will continue from there.

above is a link to videos of the runout test. It includes test using new .25 collet and .25 ground pin. History of the hiteco spindle, it has had two incidents of high vibration, first one was shortly after purchase when the fan exploded and the second about a week ago when a .5 extended length bit started pulling out the collet. This event made the collet nut much harder to remove than normal. I was able to remove the nut using the supplied wrenches. Yesterday I installed a .5mm TBN bit and noticed runout.

Oh boy :disappointed:

Yep, that half inch extended reach will kill any of the sub-$3k spindles I know of on the market. HP has nothing to with it either. That side force is critical and needs to be taken into account no mater how strong you think that spindle is. The longer the tool is the easier it is to exceed the bearings max force in the spindle.

For these machines since they are aluminum extrusion I would stick with stubbies and 1/4" or 6mm and smaller OR go really fast and very, very shallow OR so slow it will take you a friggin year to cut it with that 1/2".

Now, with foam you can get some crazy lengths but not in wood or plastic. Forget metal with anything accept a nice stubby.

PS. I do keep a ZRN Variable Flute 0.5" stubby. But in my tool description it is referenced as a “face mill” :rofl:

I hate to think I’ll have a $1300 door stop, you know anything about spindle rebuild service?

:disappointed: So sorry. If it makes you feel any better, you aren’t alone. Many people starting out make similar mistakes.

To my knowledge (which is tiny on the topic), the bearings in these cheaper spindles are pretty much the cost of the spindle. When you get anything spinning at 24K rpm it has to have very close tolerances.

You could call Alex up at CNCDepot.net and see what he thinks. Get a third opinion. He sells other brands and makes a really nice in-house model with ATC. He is in Tennessee and loves the talk about that stuff. Since he makes them and sells them he would be in a better position to answer your questions.


I see lots of posts on various forums about guys concerned about runout or things not being accurate. It’s a valid concern however there is alot of contributing factors to this.

What’s the tolerance on your endmill? Are you running high end ones with very tight tolerances or ordering from Whiteside or even AliExpress ? What is the tolerance of your endmill? The 1/2 endmill straight flute from avid is out by a few though just for example.

Second is where are you mounting your probe for checking your runout? Are all the connections tight, and it’s it a quality holder? Buying a 300 dollar caliper but using a 29 dollar Amazon special as a holder may not give us the results we are hoping for.

It doesn’t take much to show large amounts of error when it could potentially be human error being introduced.

I’m not sure if someone asked or if it was mentioned but what collet are you using. Stock one from avid or did you buy a high precision set? Once again. What’s the tolerance of the collect.

Everything has a tolerance. The more you spend the tighter those will be. Majority of us who have avid machines won’t buy the best of the best. Instead we get parts that match our budgets.

So my 2 cents is, things can compound really quickly by introducing error in the equipment being used to check for accuracy.

Not saying you don’t have an issue I’m just wanting to draw attention from another angle. And maybe give you another side to attack from.

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@Bstanga posted videos above. I think all of your questions are answered in those videos.

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First, I feel for you. As an ex machinist I would not be happy with that much runout, especially on a newer machine.
However I have to agree with the sentiment of the other replies. If you are running jobs that require an extended .5 tool or that you cannot compensate for .006 runout, then you simply purchased the wrong class of machine. All of these aluminum extrusion machines are hobby grade where a .006 clearance would be considered room for glue.

Mine will be different then yours.

Standard tolerances using a quick Google search from 1 manufacturer…

  • Cutting Diameter on Standard End Mills: +. 000/-. 002.
  • Cutting Diameter on Roughing End Mills: +. 000/-. 005.
  • Ball Nose: +. 000/-. 002.
  • Shank Diameter: -. 0001/-. 0004.
  • Radius: +. 001/-. 001.

So what my tolerance is on my endmill can’t be used for yours if your trying to get perfect accuracy. Each manufacturer has different allowances. Needs to be measured for each endmill in your possession.

Professional CNC businesses will balance there collets with the endmill to ensure the most accurate cut possible. But they are also using 100k machines and not 10k.

In his videos he was using a ground and calibrated pin, not an end mill… Just say’n.

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Just a note regarding reference to fan on top of 4hp. Mine exploded too. If you look at square body you will note cooling air passages in all 4 corners up to fan. If fan sucks anything up those it’s done. My solution sort term solution to finish a job after fan shattered was to hook a 1 1/2 pvc pipe from dust collection line angled to top of motor. So far so good. Motor runs cooler and quieter than it ever has. I’m now thinking this might be a better long term solution. Anyone think this is a bad idea?


Let me give some background info here, I have two 4896 pro’s bought about a year apart. One machine has the rotary axis on it making it effectively a little shorter I’ll refer to that as machine 1 and the other as machine 2.

I flatten quite a few slabs and do a lot of hi detail 3d carves. So it usually falls out to slabs being done on machine 2 and 3d stuff on machine 1. Last year I found out you could get the 4hp spindle and use the vfd that the came with the 2.2kw with just a couple of vfd settings and since it has a better torque curve it seemed like a good fit for machine 2 . . Here is a link to that info if anyone is interested.
So I made the purchase and installed and trammed it in. The instructions were clear that this is a higher precision spindle and must be warmed up before using. I used the spindle warm up button on Mach4 screen and let me tell you that the spindle got so damn hot you could not touch it! I immediately called Avid and talked to a young lady in support and she assured me that was normal, and that they were moving away from the CMT brand and using this higher quality Hiteco brand but they require a warmup.

I let her know that I have two air cooled spindles that can run all day and barley get warm but she assured me it was ok. After the spindle cooled down I ran another warmup and it only got warm this time, I was relieved. I never checked for runout, but being a Bridgeport mill owner I always wipe the taper out with my finger and install the bit and do a visual for runout.

Now lately I have been doing a lot of 3d crosses and last suppers using 1/16 and .5mm tbn bits. It is very easy to see runout on a bit that comes to a needle point., so I started using machine 2 for some 3d carves, and you could see a difference in the detail from machine 1 to machine 2 the carves looked almost blurry, so digging into this the runout was found. My old fingers are getting tired, but I just want to be clear the spindle was never crashed, the event with the .5 bit is a 4 inch bit that was cutting very soft cypress taking .25 cut removing material from around a crucifix that was 2" tall in Z. For what ever reason that bit started pulling out of the collet, I stopped the machine put in a new collet and finished with the same bit. Maybe the runout caused the bit to pull out. I just wanted to honest to Avid and explain all unusual events to them, which were two, the fan blowing up and the .5 bit, well three if you count the over heating.



I thought you were talking about a 0.5 INCH diameter end mill :rofl:

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I hear ya on the .5 mm bit, man it is tiny and some carves take15-30 hrs I know that sounds stupid long but if you want high detail… I wonder if I can post pictures in this forum? I don’t see a tab for files unless it is the upload tab.

I used a new collet from avid and for the test I used a .25 pin from a precision pin gage set and a .0005 DTI dial test indicator

reading was taken .5 down from the collet and in the mouth of the taper on the spindle

Its the upload button at the top of the text entry field AND I take back everything I said!


I am very happy to be very wrong :+1:

In my pea sized brain I saw you going after giant chunks of solid White Oak with a 7" long 0.5" diameter end mill :rofl:

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ha ha, no problem, I know I must look like a newbee but I’ve been fiddling with machines for quite awhile. I have a youtube channel, I don’t do much with it anymore called BS in the Shop it is mostly metal working stuff making suppressors and lathe stuff on the hobby side not a formally trained machinist. I’m retired RR conductor.

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My little shop would not meet your dust standards… lol


Bryan have you tried to check the runout of the inside taper of the spindle? If the taper is not machined on center it may cause the problem of if the taper is flat on one spot. Just a thought.


Yes I did mike, I posted a link to the videos I sent to avid I used a .0005 DTI and a precision pin and compared it to the other machine which was dead nuts. How did your build turn out?

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