Question HF350 making unpleasant noises!!

Hi,

I've a nasty feeling my HF350 is about to fail - it's been making some very strange sounds after about 20 minutes of milling today. Once the milling was finished I tried rotating by hand and it felt distinctly notchy, so I guess some of the bearings have seen better days.

It did seem better after a short cool down, though it wasn't particularly hot in the first place - it certainly wasn't too hot to handle

Anyone succeeded in dis-assembling one to service or replace bearings?

Peter

No but I had a HF350 recently which went back with my HF500 and it behaved exactly as you describe which leads me to believe that it is fitted with inferior bearings as well as a crummy control system.

Doug

Hi Doug,

So yours was showing the same symptoms - I'm very tempted to take a deep breath and purchase the same industrial spindle you have.

It must be possible to dismantle the beast to replace the bearings. Decent quality bearings shouldn't fail after a few 10's of hours in such a lightly loaded application. A set of sealed SKF's would probably put things right.

Peter.

My industrial spindle is on evaluation so I don't know if it's available to buy retail yet.

You will need to speak to Rory or Stepcraft direct on how to dismantle the HF350 but all I know is that my HF500 body unscrewed itself the last time! I was so annoyed with it that I didn't investigate any further.

I agree, a decent set of SKF bearings should see it clear for many hundreds of hours of light use.

Doug

Hi Doug,

The spindle is already advertised on the StoneyCNC website, though it does look as thought the VF inverter box is still in the prototype stage - no matter, if it works - fine.

I've contacted Rory with my tale of woe, so I hope he will be able to throw some light on the problem. I don't hold out much hope of any guidance from Stepcraft though - it took weeks of prodding from Rory to get suggestions as to how to improve the starting problems I had early last year.

Peter

In that case I recommend that you buy it!

I plan to do some cutting with it tomorrow and video it.

Doug

Look forward to seeing that - hope it comes up to expectations. I'm sure it will!!

Peter

Here is the short (5m 42s) video I took today milling a small oak insert for the upper section of my replica Brian May Red Special guitar. The job took roughly 15 minutes per side. I forgot to re-zero the elapsed time counter in UCCNC between each upper and lower cut so I don't have an accurate cut time but that's all I could capture at 1280 x 720 pixels on the remaining space on the SD memory card of my Canon Powershot G15 that I used to video it.



I was using a 4 mm four flute solid carbide flat end mill with 25 mm long cutting flutes and 65 mm overall length. There was 40 mm stickout of the spindle which uses ER11 collets.

I first drilled two holes at +50 mm and -50 mm for the steel registration dowels. I held the stock (European oak, 19 mm thick, 121.5 mm wide, 130 mm long) down with double sided carpet tape.

Feed rate: 2,000 mm/min.
Plunge rate: 120 mm/min.
Rotation speed: 20,000 rpm.
Depth per pass: 1.00 mm.

I cut down 10 mm depth then flipped over along the Y axis then ran the second cut also at 10 mm depth. I could have used a shorter cutter which would have meant that the attached exhaust would have worked but I am running with extra long cutters since my early failure. I therefore just removed the chips manually with a Dyson vacuum cleaner as you can see in the video. Sorry this looks a bit amateurish!

Job was 100% successful as far as I'm concerned and the industrial quality HF spindle is fabulous. Worth every penny of the £600 StoneyCNC is charging for it. I should add that the spindle is pretty quiet in operation IMHO. It runs up to 400 Hz (24,000 rpm). At any speeds below that it sounds like it's just idling - suspiciously quiet. The majority of the noise you can hear in the video is caused by the VonHaus ash vacuum connected to the Stepcraft exhaust system and the Dyson running.

Regards.

Doug

Hi Doug,

Wow - that's what I call a real success!!! Thanks for some really useful machining parameters too - I'll make a careful note of those when I come to machine the hardwood frames of a wooden clock I'm making.

Rory - stand by for an order!!

Peter.

Thanks for posting.

I'm liking the detachable power connector already!

Cheers,

Owen S.

Thanks chaps. I hope to have better videos ready when I start trial cuts on the guitar body half sections.

Get your wallets out lads!

I think the cutting parameters are about right Peter. The spoil is more like regular sawdust and the cutting sound as you can hear doesn't sound laboured at all.

I am going to try some ploughing on offcuts at 2.00 mm depth per cut probably on Friday.

Doug

As promised, here is a 9 minute video of some test 'ploughing' cuts this morning removing 2.0 mm depth per pass (four passes in total to 8.0 mm) on 3.6 mm plywood (hardwood throughout) faced softwood strips (simulated blockboard). The job was 100% successful AFAIC, which means that the longest roughing toolpath on my guitar body sections will be less than an hour. I might try some test cuts later today or this weekend.

Stock details
Two pieces of softwood PAR timber 315 x 44 mm x 18 mm glued to an offcut of 3.6 mm thick plywood (actual thickness 3.35 mm on digital calipers) to yield a cuttable stock volume measuring 315 x 88 x 21 mm.

- StoneyCNC industrial HF spindle
- 4 mm diameter four flute solid carbide flat nosed end mill, 25 mm flute length
- Feed rate: 2,000 mm/min.
- Plunge rate: 120 mm/min.
- Rotation speed: 20,000 rpm.
- Depth per pass: 2.00 mm.

Total cut time approximately 9 minutes.



Regards.

Doug

And a very short (1m 29s) final video for today:

Cutting an insert out of 3.6 mm thick plywood (hardwood throughout) from Travis Perkins. Same cutting parameters as above but two cuts of 1.675 mm depth per pass each.



Doug

Hi Doug,

Thanks for posting the photos and video - very impressive!! Appreciate the machining parameters too - most useful, did you get those values from Gwizard?

Rory - I want one yesterday - please!!!!!!! I think my clock frame machining will wait until I can be confident of no mid-term failures!!

Peter

Hi Peter.

Yes, confidence in this system is ramping up exponentially thank goodness!

The initial parameters of 1,500 mm/min feed rate and 375 mm/min plunge rate did indeed derive from the GWizard software.

However, after inputting a bunch of objective numerical parameters, there is a highly subjective slider bar from 100% fine/0% rough to the opposite end of the spectrum that dramatically alters the suggested feeds and speeds!

I arbitrarily selected 90% fine/10% rough to get the 1,500/375 mm/min. values. I increased the feed rate to 2,000 mm/min because the spoil was too fine (talcum powder consistency) which was clogging up the vacuum HEPA filter apart from anything else. Even at 2,000/120 mm/min and 1.00 mm depth per pass on the oak block, the spoil resembled fine sawdust indicating to me that there is some scope for further increases. I haven't analysed the spoil from today's cuts at 2.00 mm depth per pass yet.

I reduced the plunge rate because of the problems I had with drilling using the Stepcraft HF500 spindle. I left it low because it's not costing too much toolpath time and I want to be careful in case there is a problem and I need to intervene to halt the cut. A lower plunge helps with this. There was also some residual paranoia from the first rapid plunge failure that embedded the bit in my guitar neck stock and busted the HF500 PSU the first time.

I hope this helps.

Doug

1 hour 44 mins and nearly 33,000 lines of G Code later, I appear to have a Red Special guitar body lower section!

I'm very pleased with how the Stepcraft CNC machine and its spindle performed. It can't have lost one single step. Some pics attached.

Much video footage is available but needs edited because the camera stopped recording after 30 minutes and then the battery ran out.

Now we're rockin'!

Doug

Here's an hour's worth of video footage of the milling of the lower body section of the replica Brian May Red Special guitar.



There are three non-contiguous parts which I had to join together because the camera is limited to 4 GB videos at a time. The total toolpath time was 1 hour 44 minutes. I think this is plenty to give you a flavour of how it all works.

Basically there's about an hour of roughing passes. I think that's pretty much all you see here so it's a bit repetitive. Then the toolpath moves to finishing passes which you don't see (parallel which moves across the X axis taking off the bottom of the pockets, waterline which goes round the outlines taking off 1.00 mm per pass and pencil cleanup which goes around the outline and takes off a little bit).

Doug

Here's 1h 45m of video footage of the milling of the upper body section of the replica Brian May Red Special guitar.



There are some discontinuities because the camera is limited to 4 GB videos at a time. The total toolpath time was 1 hour 50 minutes comprising 9m 20s for the upper face then 1h 40m for the lower face. There is about 5 mins missing from the entire toolpath.

- StoneyCNC industrial HF spindle
- 4 mm diameter four flute solid carbide flat nosed end mill, 25 mm flute length
- Feed rate: 2,000 mm/min.
- Plunge rate: 120 mm/min.
- Rotation speed: 20,000 rpm.
- Depth per pass removed: 2.00 mm on all passes, roughing and finishing (parallel, waterline & pencil cleanup).

Doug

My HF350 is almost ready for the scrap heap!! Tried it again today more in hope than anger - more excruciating noises from the bearings!!

Reasoning that it might improve matters, I introduced some light machine oil into the collet end - this certainly got rid of the screeching noises as it ran up to speed. It still gets very hot at that end though, so the bearing(s) is undoubtedly "shot".

Any one know the strip down procedure for this spindle - it probably only wants bearings replaced as the motor seems to work fine.

I am certainly going to replace it with one of Rory's industrial grade VFD spindles - Doug is delighted with his and does some serious milling with ease now.

Peter