MT3 vs R8 spindle taper

[jcdammeyer]

So a bit of bad news: it seems I was dealing with a bait and switch seller on eBay, after chasing them for the past couple of days to switch my order to the MT3 version they told me it’s not in stock and I have to wait until next February. I opened a dispute with eBay to get my money back. Looks like I’m going to end up getting an R8 mill after all
(I don’t ever do this but for reference seller is sumaiglobal42…things escalated really badly so leaving the name here because I wouldn’t want to see anyone go through this experience)

Now I’m looking for recommendations for something similar to the PM-25 work envelope (19x7) with a brushless motor and belt drive. Any suggestions?
I’ll contact PM tomorrow to inquire about shipping but open to other suggestions.

It's really too bad that places like House of Tools and some of the other industrial ones vanished. KMS Tools has far more space dedicated to battery operated hand tool brands and what used to be a fairly nice metal working section is shoved off in the corner. So being able to buy local has changed dramatically over the last few years.

Busy Bee is gone from Vancouver for who knows how long. They used to keep a decent supply of metal working stuff too. On the island we had Island Saw and Sharpening service. They are gone.

Perhaps the market is saturated. All the baby boomers have purchased what they wanted. GenX was never that interested and the successive generations are inheriting or buying the stuff the boomers purchased.

And then there's the 3D printers. I suspect that many who would have gone into the metal hobby requiring a lathe and a mill bought a 3D printer and that keeps them more than busy enough. And indirectly I'm one of those. Although I have the sheet metal tools I rarely make a metal box. So much easier to print a plastic one.

All things being equal I'd still consider Grizzly Tools for new hardware.

 

[DavidR8]

It's really too bad that places like House of Tools and some of the other industrial ones vanished. KMS Tools has far more space dedicated to battery operated hand tool brands and what used to be a fairly nice metal working section is shoved off in the corner. So being able to buy local has changed dramatically over the last few years.

Busy Bee is gone from Vancouver for who knows how long. They used to keep a decent supply of metal working stuff too. On the island we had Island Saw and Sharpening service. They are gone.

Perhaps the market is saturated. All the baby boomers have purchased what they wanted. GenX was never that interested and the successive generations are inheriting or buying the stuff the boomers purchased.

And then there's the 3D printers. I suspect that many who would have gone into the metal hobby requiring a lathe and a mill bought a 3D printer and that keeps them more than busy enough. And indirectly I'm one of those. Although I have the sheet metal tools I rarely make a metal box. So much easier to print a plastic one.

All things being equal I'd still consider Grizzly Tools for new hardware.

I very nearly bought my wood lathe from Grizzly. Had the exchange rate been better I likely would have.

 

[jcdammeyer]

Many years ago now I had a discussion with a friend about mill prices. I bought mine new from House of Tools for I think $3300 before taxes. It seemed like a lot of money but it turns out not. Here's the simple math.

Driving really old truck. Say I wanted a new F150 that starts at $45K. Put 10% down and payments for 5 years at 9% interest run $830 per month.

Don't let your eyes glaze over just yet....

So that's $830 x 12 = $9960. OK. Old vehicle might require $1660 per year in service. Seems high but remember payments for a new one cost the same for two months.

If we reserve $1660 to maintain the beater vehicle, and pretend we'd be paying the rest for a new F150 we actually can afford a mill for $8300.

Here's one on sale for $7699 which with taxes is $8622 (remember I didn't add taxes to the truck purchase).

Buy Knee Mill Vertical Craftex Cx Series at Busy Bee Tools

This heavy duty knee mill has the power and space to make quick and accurate work of just about any machining job you can throw at it.

www.busybeetools.com

The gist of the discussion so many years ago now was that we have no trouble buying a new vehicle with payments or go on an extended holiday for $10K. But the mill has a low price limit for some reason. Yet it's actually quite easy to afford as long as you decide to forgo something else. Depreciates way less than a car. Can even earn it's price back.

 

[Dabbler]

This unit is very similar to the first mill I bought and used for just under 20 years. very good work can be one on this type of machine.

 

[Susquatch]

Yup, I don't have a fancy hammer with a socket on it so I just rap it with the butt end of the ratchet handle.

Each to his own I guess....

What do you use to seat parts in your mill vise? My vise is a self seating Gerardi Spa. I thought you had a Kurt?

........

You have been around machine tools for a million years. I'm not gunna pretend to try and break or change your habits. The following is just a suggestion for others reading this thread.

They sell these really cool tools called ratchet wrenches. Basically, they are a combination wrench with a ratchet on the box end. That's what I use on my spindle. I bought a single 3/4 ratchet wrench that lives full time on my mill. It does double duty as a vise handle too.

I suppose for those who feel the need to use the same tool to break the taper friction, one could cut the open end off and insert it into a dead blow hammer - or make a dead blow hammer end to fit it.

I much prefer to use a plastic mallet. It always breaks my R8 taper with a very light tap and never damages the hex on my spindle. It also does double duty to break the taper connection on my lathe chucks and to seat parts in my vise for those few times that is needed. There is something about the way that plastic absorbs impacts that works better than brass or hard rubber to seat parts and loosen tapers.

 

[Dabbler]

I just got one of those fancy hammer/wrench deals with a brass hammer part, used.

For over 30 years I have used a double ended box wrench: I had to order it from Sears/Craftsman in the US, as Canada stopped carrying them: It has a 3/4 box end and a 7/8 box end. The one end is for the drawbar, and the other is for the hold downs. It is also the perfect weight to give the drawbar a sharp rap.

 

[historicalarms]

Many years ago now I had a discussion with a friend about mill prices. I bought mine new from House of Tools for I think $3300 before taxes. It seemed like a lot of money but it turns out not. Here's the simple math.

Driving really old truck. Say I wanted a new F150 that starts at $45K. Put 10% down and payments for 5 years at 9% interest run $830 per month.

Don't let your eyes glaze over just yet....

So that's $830 x 12 = $9960. OK. Old vehicle might require $1660 per year in service. Seems high but remember payments for a new one cost the same for two months.

If we reserve $1660 to maintain the beater vehicle, and pretend we'd be paying the rest for a new F150 we actually can afford a mill for $8300.

Here's one on sale for $7699 which with taxes is $8622 (remember I didn't add taxes to the truck purchase).

Buy Knee Mill Vertical Craftex Cx Series at Busy Bee Tools

This heavy duty knee mill has the power and space to make quick and accurate work of just about any machining job you can throw at it.

www.busybeetools.com

The gist of the discussion so many years ago now was that we have no trouble buying a new vehicle with payments or go on an extended holiday for $10K. But the mill has a low price limit for some reason. Yet it's actually quite easy to afford as long as you decide to forgo something else. Depreciates way less than a car. Can even earn it's price back.

still a belt driven machine A LOT of money to change belts every time you need a tool speed change, personally I would very much prefer any used gear driven machine with transmission at 1/2 the price regardless of tool mount provisions.

 

[historicalarms]

Any box end or ratchet end wrench wouldn't work on my draw bar head...When I set a taper into the socket I dont just "snug" it up, I tighten it securely and that damn bar head gets peened something awful with the force of very firm hammer whacks it takes to release the taper.
In 20 yrs of using the same draw bar & MT tooling I can see no damage to either except that hex head.

I have had the taper (drill chuck) turn a couple times in my lathe tailstock (no draw bar of course) but never has one come loose in the mill LOL

 

[jcdammeyer]

still a belt driven machine A LOT of money to change belts every time you need a tool speed change, personally I would very much prefer any used gear driven machine with transmission at 1/2 the price regardless of tool mount provisions.

Or replace the single phase motor with an AC Servo and run 1 RPM up to 3000 RPM.

 

[StevSmar]

…and some ridiculous customs clearing fees…

PM charged me around 1% of my purchase cost for brokerage of my Mill. I considered that a bargain to allow the Mill to show up in my driveway with no effort on my behalf.
(except for financial effort of course…)

 

[Darren]

Sigh....sorry I have to write this....

OMG OMG no pin, pin broken, what am I to do????? Take it to a machinist to fix it.....W A I T!!! (Insert your won name here) I am a machinist, problem solved.

You guys so funny.

I don't have a pin in my R8 mill, and don't miss it. If R8 was going to slip, 3/4" TTS would slip like crazy.

 

[Eyecon]

So folks another decision to be made since the eBay deal fell through. PM-25MV or LMS 6700? I got quotes from the two companies including tax, freight, brokerage etc. Basically I can get the LMS 6700(SIEG SX3.5) for the same price as PM-25MV with a DRO, a table and a set of R8 collets. The only reason I'm more attracted to the 6700 is the 1000W motor and 5000RPM top speed. I plan to do a CNC conversion for the mill as mentioned before so while I don't really need the DRO, the linear scales will come in handy for CNC encoder feedback on all axis.

I'm paying a lot more than I initially planned anyway but I'm not sure which is the better machine in terms of quality and if the extra travel and motor on the 6700 is worth giving up all the other goodies that will come with the PM

Thoughts/recommendations/advise?

 

[Former Member]

Look no matter what manual mill you buy you will have to do internal upgrades at some point (ie to ballscrews) because CNC will wear your leadscrews because of the increased usage, remember CNC can keep cranking when the human is exhausted.

Second you will need to stay on top of your ways and keep them snug and oiled.

I've converted my BB CT054 (now a CX603) to CNC.

I am less concerned about having linear scales as I don't use or recommend steppers. Servos are the way to go (and they are quieter). The best alternative is Teknic's Clearpath SDSK servo which has a encoder built in handles step and direction signals (ie stepper input) and size for size out performs steppers.

Also consider a BB CX611.

Best recommendation I can give is get a machine, get milling and have a blast.

 

[Eyecon]

Also consider a BB CX611

I looked at that but at 1800 rpm and 6” of y travel it doesn’t seem like a good option for 3400 cad. I also didn’t think the front mounted Z handle would make it a good candidate for CNC conversion.

I am less concerned about having linear scales as I don't use or recommend steppers. Servos are the way to go (and they are quieter). The best alternative is Teknic's Clearpath SDSK servo which has a encoder built in handles step and direction signals (ie stepper input) and size for size out performs steppers

I’m not too sure about that. I get servos for sure in terms of speed and torque under certain conditions. But with the affordable lower grade ball screws that we all use for these conversions, and lost motion because of ways vs linear guides, I’d rather get feedback and correct the output based on the actual position of the table not the motor shaft.

Best recommendation I can give is get a machine, get milling and have a blast.

Roger that!

 

[jcdammeyer]

I don't have a pin in my R8 mill, and don't miss it. If R8 was going to slip, 3/4" TTS would slip like crazy.

My understanding of the pin is that it's there to prevent the Collet from turning while the turning draw bar pulls it up and starts to apply tension. Once that's started the pin doesn't do anything anymore. Which, as you've said, must be true if you don't have one and your collet hasn't spun.

 

[Susquatch]

My understanding of the pin is that it's there to prevent the Collet from turning while the turning draw bar pulls it up and starts to apply tension. Once that's started the pin doesn't do anything anymore. Which, as you've said, must be true if you don't have one and your collet hasn't spun.

Yup, that's what I said above too.

I'd only add that my mill has extremely low turning resistance. I like the assistance that the pin gives me.

 

[Darren]

If i used R8 collets in the spindle nose more, I think I'd probably want the pin. With the power drawbar and the tooling I use I haven't had an issue just holding onto it while tightening

 

[Susquatch]

If i used R8 collets in the spindle nose more, I think I'd probably want the pin. With the power drawbar and the tooling I use I haven't had an issue just holding onto it while tightening

You have just hit on the one reason I might want a power draw bar. Till your note just now, I have not considered it.

My issue is holding tools in place while I tighten the draw bar. I only have two hands. And I'm not about to hold a sharp cutter in my mouth! One hand to hold the endmill tool, another to hold the spindle, another to hold the brake, and still another to crank the drawbar wrench... Yup, a power draw bar might come in handy!

 

[jcdammeyer]

Yup, that's what I said above too.

I'd only add that my mill has extremely low turning resistance. I like the assistance that the pin gives me.

As long as my system is enabled the AC servo locks the spindle so other than spinning the pulley in the belt it's not much of an issue.

Now, if you add a WUT underneath your draw bar nut then you can hand turn the drawbar until it captures the collet. Keep turning until the drawbar snugs up. Then grab two wrenchs, one for the WUT and one for the draw bar and heave at it.

 

[jcdammeyer]

Just to add some photos here. The WUT sits under the draw bar. In this case the round part and the nut of the draw bar are all one piece even if it might not look like it. The shoulder on the draw bar registers in the WUT.

Ideally the WUT would have a shoulder that registers inside the spindle but there isn't room for that. I'd have to remove the spindle and bore a larger hole in the top.

Anyway, add a 24mm wrench to keep the WUT from turning as in this photo.

I set my large torque wrench to 25 ft-lbs and tightened until the wrench went click signalling 25 ft-lbs. I was able to keep the spindle from turning by just hanging onto the 24mm open end wrench with my left hand.
It took a bit more than 25 ft-lbs to undo but again, once loose enough to turn by hand I can catch the TTS tool holder or keep going to drop out the R8 collet.

One doesn't really need a spindle lock. I installed this WUT on my mill right after the Home Shop Machinist article came out maybe 10 years ago? Amazing how well it works.

One day I'll pull the spindle out and create a registration hold for a WUT with a shoulder.