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View Full Version : Is the Prazi BF400 Milling Machine worth the price?



winchman
08-11-2003, 08:30 PM
I'm thinking about getting a milling machine a bit larger than my Sherline 5400. I don't have the room for, or a way to handle, a large machine, and the floor of my shop isn't strong enough for the heavy load anyway.

The 200-pound Prazi BF400 Milling Machine
looks like it would do the job and fit in the shop without busting the floor.

Is it worth the price and is it as good as it looks?

Roger

Thrud
08-12-2003, 04:40 AM
Roger

For its size they are excellent. If you can swing it go for the one with VS and ball screws. It is a dream to convert to CNC wit ball screws.

Be aware that tooling in a MT#2 spindle is limited to 5/8" endmills. MT#2 is slightly better, NT30 would be the best overall choice (but expensive plus I am not sure if NT30 is available on that particular machine).

It is capable of heavier work than the Sherline but very light work in comparison to a mid sized milling machine (baby bridgeport). No free lunch. They can do some lovely smaller precision work.

I have a Maximat 7 and find its limitations to be mostly size related (wish it was 4 times bigger). But it excels at fine work!

jeastwood
08-12-2003, 02:58 PM
I have one. I also have the 5400 mill. I liked my Sherline mill a lot, but as in your case, wanted something a bit bigger. I was able to see the BF400 at the PRIME show last year, and get it for $2000, so that made it worth it for me.

I've been quite happy with the mill. I was able to reuse all of my Sherline mill tooling by using an MT1 to MT2 adapter.

It's just possible for one person to carry down the stairs into your shop and setup. It comes apart into 3 pieces, so each is manageble.

By using a 1/2" shank end mill holder, you can obtain end mills up to 1" in diameter and use them. I've used a 3/4" with no problems; in fact, the bigger end mills work more smoothly than the 3/8" shank sizes, not surprisingly.

winchman
08-12-2003, 06:59 PM
Most of the work I do is in aluminum and I rarely do any heavy cutting. Even with the spacer on the Sherline, I keep running into the column with some of the odd shaped pieces.

Being able to continue to use the most of the end mills I've bought for the Sherline is an important factor. It's good to know I'll be able to do that with an adapter until I can invest in some larger ones.

Thanks for the input.

Roger

Thrud
08-12-2003, 07:17 PM
Roger
I like your website, BTW.

I have a three insert carbide face mill these are about the maximum that should be used on a MT#2 shank and lighter cuts are a must. Aluminum you should be able to go nuts with and crank up the RPM's. SOme of the full line suppliers may have these still, if not you can purchase them from the UK - but you will need to purchase or make a Whitworth (usually 3/8"BS) drawbar for those.

I would not suggest using an adapter to use larger endmills - I would suggest that you make a proper shank if you insist on doing this and insure that it is equipt with a drawbar to retain it in the spindle.

USE A DRAWBAR AT ALL TIMES IF AT ALL POSSIBLE! Even a light cut can pull a MT#2 loose if no drawbar is used. I would also suggest that your Sherline tooling if used with a sleeve to adapt it to the new spindle that it too must have a drawbar. Your new machine will have far more torque than the Sherline. And if using a boring head, insure that its shank is also native to your spindle - no adapters!

Safety first!

winchman
08-12-2003, 07:18 PM
That sounds like some good advice. I don't much like the thought of something sharp and turning fast coming loose from the machine.

I mostly use the Sherline with the rotary table to lay out hole patterns and start the holes. I do all the actual drilling on my trusty old Craftsman drill press, since the holes are often 1/2" or more. Being able to do the whole job on one machine will be a real plus.

Roger

[This message has been edited by winchman (edited 08-12-2003).]

jeastwood
08-13-2003, 02:02 PM
I agree with the suggestion to use draw bars; I drilled a hole in the end of the tang on my MT2 to MT1 adapter so that I could do that very thing.

The deeper throat and more cross travel on the BF400 was a real selling point to me too, although the extra Z height is what I use the most.

Thrud: I have bored using my adapter arangement, again with a draw bar. I'm interested in why you strongly recommend no adapters for boring?

Thrud
08-14-2003, 03:52 AM
jeastwood:
It is more a point of rigidity and accuracy than anything else. If you are going to the trouble of useing a boring head on a piece, the accuracy (goes hand in hand with finish) is obviously the reason for doing so. Never use a straight shank boring head in a collet! Take the damn shank off and put (a native spindle taper adapter, i.e. MT#2, NT40, R-8). Note that for MT#2 7/8"-20 threaded heads are the largest you can use with a standard shank - Criterion does make a 7/8"-20 to 1-1/2"-18 adapter these are precision ground for concentricity and cost as much as their shanks!

The use of adapters such as a MT#1-MT#2 adds errors and if you think on it a bit, it limits the maximum torque that can be used. I am not saying you can't do it, I am saying you should not. I understand that life constrains us from doing everything the way it technically should be done - sometimes one has to "make do" with what you have. That can get you into trouble - damaging a workpiece that took days to make, or even worse causing injury or death.

And ALLWAYS use a drawbar equipt shank - the MT taper is not reliable without it. I won't put any shank in my Maximat without a drawbar. A "Spindle-mate" socket cleaner is a good way to keep tht expensive spindle in top notch form - cheap insurance.

Safety should be our first concern. Doing things according to established standards can reduce headaches, increase cutting time, reduce screwups, and reduce or eliminate sources of safety issues.

jeastwood
08-14-2003, 09:19 PM
Thrud: you've inspired me to look into getting an MT2 boring head for my BF400.
Rigidity is king here; looking at MSC and Travers, looks like I can get a head that accepts a 7/8"-20 MT2 shank plus the shank for ~ $200. The Sherline boring head that I'm using is OK, but it is pretty lightweight.

Thanks again for the info,