variant22 14th February 2013, 12:46 PM I am in my 3rd month of ownership of a new gear head mill (SM-MD45 aka HM46 equivalent) with a 1.5hp motor. I am getting major chatter and vibrations through the head when fly cutting steel using an indexable fly cutter with 45deg carbide insert (feeding by hand). Any depth of cut more than say 0.1mm causes chatter and vibrations. I also get the same type of noises when drilling large (13mm) holes from smaller pilots. I have noticed some bubbles (not a lot) in the ISO 68 hydraulic oil in the gear box glass window.
The tram, is good, gibs are tight, bolts on head are all tight, spindle run-out is 0.01mm. It all works fine with Aluminum but really starts to struggle when facing steel.
According to other owners this mill (RF45) should be able to face steel without vibrations or chatter even at a much greater depth.
Any ideas what I should be looking at to resolve this issue? I am at the point where I may well rip the head off and inspect the gearbox for anything suspect. I wanted to check here first in case there are something obvious to look at before I start ripping it apart.
Big Shed 14th February 2013, 01:25 PM First thing I would check is run-out on the spindle, particularly at the depth of extension you are working at.
What type of spindle is it, MT4 or R8?
You are using the drawbar I am assuming?
Next thing would be to check how well the work is being held down.
Stustoys 14th February 2013, 01:48 PM Is it showing chatter on the workpiece or does it just sound terrible?
What rpm are you running? what dia is the cutter?
Its a single toothed cutter? if so then runout doesnt matter.
Sure you arent climb milling?
I dont recall what the drawbar is like on these machines. Is there a smooth section you can rub your fingers against?*
I'm guessing its just backlash in the gears or the spindle, running your fingers on the drawbar provides some drag so they dont clatter about. Though I dont have a real fix. While it can sound shocking I'm not sure how much damage it does?
I assume you are feeding with the X, if so moving the Y
so the cutter loadsup slower or unloads slower might help.
Stuart
*just to be clear I'm talking about at the top of the machine.
p.s. was it you that made his own fly cutter? is this the one that has issues?
variant22 14th February 2013, 02:33 PM First thing I would check is run-out on the spindle, particularly at the depth of extension you are working at.
What type of spindle is it, MT4 or R8?
You are using the drawbar I am assuming?
Next thing would be to check how well the work is being held down.
I have not checked the run-out at depth. I checked it full up and it was 0.01mm. I will extend the quill and check. I am running an R8 spindle. The arbor of the fly cutter is 3/4 and it is mounted in a 3/4 R8 collet.
I am using the standard R8 7/16 drawbar into the 3/4 R8 collet.
The work is in the vise on parallels. 25mm square steel not extending past the vise jaws. It is tight and rigid.
Is it showing chatter on the workpiece or does it just sound terrible?
It is showing chatter in the workpiece. It shows some ~1.5 to 2mm wide concave streaks in the direction of travel.
What rpm are you running? what dia is the cutter?
I have tried different RPMs from ~450 to 1,600. With 1,000 being the main one I have been using as this is what Tormach does on their demo video with the same fly cutter. Cutter diameter is around 8cm total.
Its a single toothed cutter? if so then runout doesnt matter.
Single carbide insert - Tormach SuperFly.
Sure you arent climb milling?
I have tried traveling both directions. It does not make much difference.
I dont recall what the drawbar is like on these machines. Is there a smooth section you can rub your fingers against?*
I'm guessing its just backlash in the gears or the spindle, running your fingers on the drawbar provides some drag so they dont clatter about. Though I dont have a real fix. While it can sound shocking I'm not sure how much damage it does?
The drawbar is one that has a thread on the top and bottom and smooth in the middle section. It oscillates quite a bit when the machine is running. I have 2 drawbars and they both do this. I am not sure if it needs some sort of tapered bushing to stop this.
It sounds like backlash in the gears. It was enough however to stall the cutter once. It sounds like something is going to give way which does not make much sense. Others with this machine have reported that there is no vibration and it cuts through like butter. I am not seeing it at all. Completely the opposite.
I assume you are feeding with the X, if so moving the Y
so the cutter loadsup slower or unloads slower might help.
I have tried moving the Y and it really makes no difference. I end up with the same noises and a similar result.
The fly cutter is a Tormach SuperFly. Beautiful piece of tooling.
Edit: For the record, I have got better cuts than the one pictured. This one however illustrates the issues best.
254272 254274 254273
pipeclay 14th February 2013, 02:56 PM Don't worry about the Climb milling, doesn't play a part in facing.
Do you have any tips with a different nose radius on them.
Wouldn't be overly concerned about bubbles in your oil,after all it is a gearbox with parts spinning in oil at high RPM.
Is it possible to move the cutting tool further back into the fly cutter body to reduce the amount of tool over hang.
Do you have a Face mill indexable tool,if so do you get the same results with it.
morrisman 14th February 2013, 03:01 PM Hi
The fly cutter I use in the DM 45 Mill/Drill is the R8 fly cutter from CDCO , it uses a hss ground tool bit , held in by 3 screws . It works fine .
I've never seen a carbide insert flycutter tool like that one pictured ... The insert itself may be giving you issues ? Is it the correct insert e.g., angles etc. Mike
Dave J 14th February 2013, 03:07 PM Just a thought looking at those ripples, have you checked you spindle bearing for slop? They may have settled in from new (or never been adjusted right) and need adjusting.
I would pull the quill out and disassemble the spindle, you will more than likely find what looks like white cooking fat as grease. After cleaning everything up with a bit of kero or similar, use some high quality wheel bearing grease and adjust the pre load. At least then you know you have eliminated that area and it's properly greased.
Also when machining keep the quill in as much as possible and locked.
Dave
Dave J 14th February 2013, 03:11 PM Hi
The fly cutter I use in the DM 45 Mill/Drill is the R8 fly cutter from CDCO , it uses a hss ground tool bit , held in by 3 screws . It works fine .
I've never seen a carbide insert flycutter tool like that one pictured ... The insert itself may be giving you issues ? Is it the correct insert e.g., angles etc. Mike
Hi Mike,
Have a look at this home made carbide tipped fly cutter, it's a work of art (could be another project for you). Rob joined here a few years back but mostly posts on the Madmodder forum as he is from the UK.
Fly Cutters (http://madmodder.net/index.php/topic,7987.0.html)
Dave
variant22 14th February 2013, 03:48 PM Don't worry about the Climb milling, doesn't play a part in facing.
Do you have any tips with a different nose radius on them.
Unfortunately I do not have any others of the same shape. I have the cemented carbide (pictured) and the polished type for aluminum. These were supplied with the fly cutter by the manufacturer. The one pictured was at the end of the run after it had taken a beating. Surprisingly the insert still looks in good shape.
Wouldn't be overly concerned about bubbles in your oil,after all it is a gearbox with parts spinning in oil at high RPM.
Thanks for mentioning this. I will not look too much into it. It is certainly not foaming right up or anything.
Is it possible to move the cutting tool further back into the fly cutter body to reduce the amount of tool over hang.
I will have to give this a try. The cutter is very rigid however and is not out as far as shown in the Tormach demo video (see below for the link).
Do you have a Face mill indexable tool,if so do you get the same results with it.
Unfortunately not. I have been trying to convince myself to pull the trigger on one of those small Glacern 45 degree indexable face mills. I keep reading however that the fly cutter will out perform the face mill as the fact it has a single insert does not hog the horsepower of the motor. I am not sure either way.
As a side note, 13mm drilling into aluminum can give off similar noises.
Hi
I've never seen a carbide insert flycutter tool like that one pictured ... The insert itself may be giving you issues ? Is it the correct insert e.g., angles etc. Mike
Yes. This is the one Tormach supplied and you can see the performance it gives in this video: Tormach-Fab Lab Skill Builder: Fly Cutting with a Tormach Superfly Cutter - YouTube (http://www.youtube.com/watch?v=01Rc5BmtDLA) (note about 3min in).
Just a thought looking at those ripples, have you checked you spindle bearing for slop? They may have settled in from new (or never been adjusted right) and need adjusting.
I would pull the quill out and disassemble the spindle, you will more than likely find what looks like white cooking fat as grease. After cleaning everything up with a bit of kero or similar, use some high quality wheel bearing grease and adjust the pre load. At least then you know you have eliminated that area and it's properly greased.
Also when machining keep the quill in as much as possible and locked.
Dave this is all good advise regarding the bearing slop/quill. I have not checked the spindle bearing at all. I will have to check the bearing and pull out the spindle. I am not sure how to adjust the pre-load so I will have to research that one.
As a general rule when milling I try to keep the quill up as much as practical. "Quill is for drill" right? :)
Stustoys 14th February 2013, 03:48 PM Wow thats chatter.
Forget everything I said...... :D
Don't worry about the Climb milling, doesn't play a part in facing.
Sure if you make a couple of reasonable assumptions. I was checking the unreasonable. Given the pictures the problem is elsewhere.
Stuart
PDW 14th February 2013, 04:19 PM Unfortunately not. I have been trying to convince myself to pull the trigger on one of those small Glacern 45 degree indexable face mills. I keep reading however that the fly cutter will out perform the face mill as the fact it has a single insert does not hog the horsepower of the motor. I am not sure either way.
If that were true industry would use fly cutters. They don't.
The loading/unloading of your fly cutter at speed as the tip enters & leaves the cut is a recipe for vibration and chatter. A 3 or 4 tooth face mill has at least 1 tooth in the cut at any time thereby preventing this variable load.
It takes X HP to remove Y cm3 of metal per minute. The only way a face mill will remove less than a fly cutter is if the rpm, DOC or feed is radically different - or the tip geometry is worse. Depends on what the limiting factor is.
FWIW I would *never* run an 80mm fly cutter at anything like 1000 rpm in my Bridgeport. Maybe 150 rpm as a starting point - this is over 100 sfm. Yeah I mix up imperial & metric units.....
PDW
pipeclay 14th February 2013, 04:20 PM Have you tried increasing the depth of cut.
In normal operation with use of a face mill depths of cut of upto 3mm should be achievable on your machine.
I would also think that cuts of upto .5/.75mm should be achievable with the fly cutter.
When you have been running the cutter at 400/1000 RPM have you been able to produce something like the 250mm/min feed rate.
You may find if you can increase the feed rate that the vibration problem may reduce if not already at or about the stated feed rate.
,if the feed rate is to slow this could be causing some of your vibration.
Not sure if you already have any temporary swarf gauding on the mill but at those speeds and feeds it would be advisable,For Sale signs or similar are good to use,just cut to size and lay in the tee slots or support some other way.
nearnexus 14th February 2013, 04:35 PM Wow, that is pretty severe chatter.
By putting your hand on each section of the mill, mill table, quill etc when cutting you should be able to feel where the chatter is being generated.
There will be some serious shudder being generated when scouring like that occurs.
Something is loose (bearings, gears, gear head, work mount) to get that much marking.
You could try putting a long bar in your largest collet and the table vice (separately), and with the machine off, apply leverage and look for movement. Use a dial indicator on it.
Also heavily oil the gibs and when levering on the various components look for oil squelching in and out of the ways - shows movement very easily.
Don't over do it, you only need light/moderate pressure.
Rob.
variant22 14th February 2013, 04:53 PM If that were true industry would use fly cutters. They don't.
This fly cutter is specifically engineered for small machines. Tormach have a great article on the development (TTS SuperFly Cutters: A Modern Update to an Old Shop Standard « Milling Around (http://www.tormach.com/blog/tts-superfly-cutters-a-modern-update-to-an-old-shop-standard/)). Tormach reported far better performance on their small mills with the fly cutter than their indexable face mill. The article goes into some detail on why this works better than a face mill on a 1.5hp machine.
The loading/unloading of your fly cutter at speed as the tip enters & leaves the cut is a recipe for vibration and chatter. A 3 or 4 tooth face mill has at least 1 tooth in the cut at any time thereby preventing this variable load.
Yes, but apparently they take significantly more horsepower.
FWIW I would *never* run an 80mm fly cutter at anything like 1000 rpm in my Bridgeport. Maybe 150 rpm as a starting point - this is over 100 sfm. Yeah I mix up imperial & metric units.....
Believe it or not, at 1,000rpm I get the best finish and least chatter. It was what Tormach were using on their mill which is apparently less rigid and has less power than the RF45.
Have you tried increasing the depth of cut.
In normal operation with use of a face mill depths of cut of upto 3mm should be achievable on your machine.
I would also think that cuts of upto .5/.75mm should be achievable with the fly cutter.
To be honest I have been a bit gun shy on this. I did not want to wreck anything. I might have to try a bit deeper and see how it goes. I am however convinced that something is up with the gear drive as others with the same mill have had excellent results. Mine so far do not match up to where they should be.
When you have been running the cutter at 400/1000 RPM have you been able to produce something like the 250mm/min feed rate.
You may find if you can increase the feed rate that the vibration problem may reduce if not already at or about the stated feed rate.
,if the feed rate is to slow this could be causing some of your vibration.
Yes, I have been able to do 250mm/min. I have tried a variety of feed rates. I try to be as consistent as possible with the wheel. I have been paying attention to the sections (feed rate) that produce better results.
Not sure if you already have any temporary swarf guarding on the mill but at those speeds and feeds it would be advisable,For Sale signs or similar are good to use,just cut to size and lay in the tee slots or support some other way.
The machine does have a perspex guard (which incidentally keeps dropping out - note to manufacturers: something about threading plastic is not a good idea) but it is not useful for stopping the swarf exiting from the sides. It is however on my "todo list" to make a full enclosure. I just finished up the 3 axis DRO install (took a couple of weeks as I had to machine all the mounts and cut down the guards) and the next cab off the rank is a power drawbar. Then the enclosure will come next. It has literally been non-stop work since I purchased this mill. I purchased it to make parts for my car, yet I have spent all my spare time making parts for the mill.
I was only playing with some mild steel to make a few more (I have a standard clamp kit) tee-nuts in both M12 and M8. I am also making a few clamps for use on the table per one of Harold Halls books.
variant22 14th February 2013, 04:54 PM Wow, that is pretty severe chatter.
By putting your hand on each section of the mill, mill table, quill etc when cutting you should be able to feel where the chatter is being generated.
There will be some serious shudder being generated when scouring like that occurs.
Something is loose (bearings, gears, gear head, work mount) to get that much marking.
You could try putting a long bar in your largest collet and the table vice (separately), and with the machine off, apply leverage and look for movement. Use a dial indicator on it.
Also heavily oil the gibs and when levering on the various components look for oil squelching in and out of the ways - shows movement very easily.
Don't over do it, you only need light/moderate pressure.
Rob.
Thanks Rob. These suggestions are helpful. I will print them off and give it a try. I will report back the results.
Dave J 14th February 2013, 05:56 PM This fly cutter is specifically engineered for small machines. Tormach have a great article on the development (TTS SuperFly Cutters: A Modern Update to an Old Shop Standard « Milling Around (http://www.tormach.com/blog/tts-superfly-cutters-a-modern-update-to-an-old-shop-standard/)). Tormach reported far better performance on their small mills with the fly cutter than their indexable face mill. The article goes into some detail on why this works better than a face mill on a 1.5hp machine.
Yes, but apparently they take significantly more horsepower.
I just finished up the 3 axis DRO install (took a couple of weeks as I had to machine all the mounts and cut down the guards) and the next cab off the rank is a power drawbar. Then the enclosure will come next. It has literally been non-stop work since I purchased this mill. I purchased it to make parts for my car, yet I have spent all my spare time making parts for the mill.
A fly cutter should give superior results to a face mill, but you will have no problem running a 50mm face mill in your machine and it will remove metal a lot quicker than a fly cutter.
I Have a few of the CTC face mills and they are only about $150 with 10 inserts, good value for money in my book.
For the spindle bearings you just do them up until there is no play, then install in back in the machine and check the temperature. You should be able to hold your hand on it, if it's cold after 10-15 minutes it's too loose, if you can't touch it because it's too hot they are too tight. As far as I know this is the best way to check the pre load.
This thread might help you out, I know it's not the same as your mill but they are similar. I also know there is article on the internet about your size machine and doing spindle bearing, there may even be a link to it in the thread below. If you cant find it let me know and I will chase it up for you.
http://www.woodworkforums.com/f65/changing-top-quill-bearing-taper-one-hm52-126514/
Now the DRO installation, any chance on pictures? It could help out other down the track doing the same.
I placed my scale on the front of the table to save the X scale taking up and Y travel
http://www.woodworkforums.com/f65/installing-dro-scale-front-table-hm50-52-a-115786/
I have just been talking to another member here about a power draw bar, I have had my new air cylinders and impact wrench's for around 3 years and am only just getting around to it now, LOL I am putting one on my vertical and one on the horizontal using linear bearing. I think I only paid around $70 for the rod and bearings for both, so I think it's worth while in the long run.
What design are you going with, manual or full automatic?
Dave
simonl 14th February 2013, 11:11 PM Hi Variant22,
I don't want to tell you to eat eggs or insult your intellegence but since you will no doubt want to leave no stone unturned, I will ask the question: Are you sure the spindle is travelling Forward and not in Reverse?
I'm almost embarrised to mention this but what the hell! I recently converted my 45 mill to VFD. The night that I finally mounted the newmotor to the head and wired up the VFD I gave it a run. It was late at night and I was tired and had tunnel vision of how my adapter plate would work and how the new bearings would sound and how the VFD parrameters were set. When I finally got to making chips I was most devistated and disappointed at the amount of vibration and chatter, even for very very modest DOC and feedrates. No amount of adjustment on my U beaut POT speed control would fix it............. You can imagine the simultaneous relief and embarissment when it dawned on me that the motor was running in reverse!
The poor endmill. It never stood a chance :B
Cheers,
Simon
nearnexus 15th February 2013, 09:29 AM Hi Variant22,
I don't want to tell you to eat eggs or insult your intellegence but since you will no doubt want to leave no stone unturned, I will ask the question: Are you sure the spindle is travelling Forward and not in Reverse?
Cheers,
Simon
Ha Ha, who hasn't ever run their gear in reverse :)
You are not alone.
Rob
PDW 15th February 2013, 10:34 AM This fly cutter is specifically engineered for small machines. Tormach have a great article on the development (TTS SuperFly Cutters: A Modern Update to an Old Shop Standard « Milling Around (http://www.tormach.com/blog/tts-superfly-cutters-a-modern-update-to-an-old-shop-standard/)). Tormach reported far better performance on their small mills with the fly cutter than their indexable face mill. The article goes into some detail on why this works better than a face mill on a 1.5hp machine.
Yes, but apparently they take significantly more horsepower.
That's because the Tormach *has* no power. Their fly cutter must have a cutting edge geometry to do what it can to compensate for this. You must pay for this in either shorter life of the cutting edge or increased machining time - shallower DOC or slower feed. There's no free lunch.
TCT tooling is used because it works, provided you have the HP to drive it. A Tormach doesn't so they have to do what they can. Trying to extrapolate the workaround for a toy machine to a bigger one is simply wrong. Given the results you're getting, either using the fly cutter is not correct or something is wrong elsewhere. I do know that using a fly cutter is going to hammer your bearings. I can run a 50mm 3 tooth TCT face mill on my 3/4HP B/port motor, at 0.100 DOC, fast enough to have blue chips and a shiny surface. R8 taper. As soon as the cutting edges get blunt, power needed goes way up and the cutter starts hammering. I can run a single point fly cutter on my horizontal mill at around 40 rpm, 6" sweep, .040" DOC and slow feed to get nicely finished surfaces on hot rolled angle iron. The baby horizontal mill has a very rigid spindle ad I use a hand-ground & honed HSS toolbit in the cutter body not carbide. Fly cutters need a rigid setup, to run fairly slowly and to enter the work at as shallow an angle as possible to minimise the shock loads.
I'm not going to engage in an endless debate over it. Believe what you wish. How I do it works.
PDW
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