[keithmcelhinney]

I need to mill a pocket that is going to be very deep ~4.5" in aluminum. It will have one wall that is that deep and the other walls will be ~2.5" so chip clearance shouldn't be an issue. I have the tormach modular insert cutter which may be close but I am thinking maybe a shear hog and then a long 1" endmill for finish. There are no sharp interior corners so I could use something bigger if need be. Do you think I should just plunge rough then use the big shear hog? Any thoughts would be appreciated.

I had a problem with the modular cutter but I have a feeling it was because the tram was off a bunch when I tested it. Going to test it again this weekend.

-Keith

[AUSTINMACHINING]

That's a lot of depth. I would go for the largest Shank tool I could find depending on your corner rad requirements. I got a r8 to er32 collet to use a 3/4" diameter, long indexible chamfer mill that worked well. I also have a 4" reach 1/2" reduced shank endmill. Max step over is about .015, so light cuts are required, but it works well. Plunge roughing sounds like the fastest way to remove the bulk of the material, then use the most rigid tool possible . I've used a 1/2" drill to make a starter hole before helical boring which makes things go faster. That shear hog sounds cool if they can go that deep, although I would prefer a direct 3/4" shank (no TTS).

[SCzEngrgGroup]

Keith,

You might consider using a BIG drill bit to remove most of the material. Plunge roughing with an endmill is really hard on the tool, and I think you'd have a hard time making it work well at that depth. You could really benefit from HSM techniques as well. Using something like the ShearHog with HSM toolpaths you should really be able to haul a$$, especially if you start with a lare diameter helical entry to create some working room.

That said, I think rigidity. or lack thereof, is going to be a major issue at that depth.

Regards,
Ray L.

[warrenb]

Plunge milling is your friend in this situation.

Endmills have a cutting tooth about .0005 smaller than the shank diameter so you'll have to do some step-ins every flute length to avoid rubbing.

[keithmcelhinney]

I did some test cuts with the 17mm modular endmill with the long extension this weekend. The screaming I had using this before was definitely because of the tram. I am going to doing some more tests later but I think this is doable. I am going to see about getting the part roughed with a water jet I think. This will take a lot of the material out of the center as well as the profile that should be able to cut down my cut time significantly.

-Keith

[EZfab]

I often machine pockets that are between 3-4 inches deep and sometimes are deeper than they are wide. I don't do a lot of them so I don't waste my time with quick stock removal. For the work I do, I often find it minute wise and hour foolish to spend too much time perfecting tool paths that speed as much material away as possible. I spend 5 minutes on the code and let the machine cut for a longer time while I do something else.

For all of my deep hole stock removal I use 1/2 x 4 or 6 x .5 LOC 2 flute solid carbide endmills. Although I need to order more and have been doing the same thing with 1"LOC and getting only slightly more chatter than the 1/2" LOC,

2200-2400 RPM
.08-.10 cut depth
.25-.30 step over.
25 ish ipm. sometimes I ignore the chatter noise and cut at 35-40 ipm if I need to.

This works generally well for me. It's much easier in cast plate than 6061. It takes a little time at these speeds but for what I do it's fine. And I spend that time working making money.

Greg

[keithmcelhinney]

Greg thans so much! Can I ask where you get the endmills. I have been hard pressed to find a long endmill with such a short LOC.

[SCzEngrgGroup]

I would think if you want a long endmill with short flutes, a good insert tool would be a much better choice...

Regards,
Ray L.

[EZfab]

I would think if you want a long endmill with short flutes, a good insert tool would be a much better choice...

Ray, any suggestions and where to begin looking? I have not bought any insert tooling in my life. I have made a few attempts to look for something, but there are so many options, brands, inserts etc that I get overwhelmed and revert back to what I know.

Greg thans so much! Can I ask where you get the endmills. I have been hard pressed to find a long endmill with such a short LOC.

There's a few companies out there that make them. The last pcs I used were purchased years ago when I had the money to keep a good stock of end mills. I have been working from home using up that stock for the past 2 years and still ahve a good 2 years supply ahead of me. I don't have a clue what these end mills would even cost today. IMCO has a line called Streakers, they have a 0.500 x 0.625 LOC x up to 6" long but this is a high end product and i think expensive. The mills I used were made in India. They chatter a lot and will chip so you don't want to spend a crap load of money of them. Maybe Ray is right with the insert tooling...??? also, get corner radiused because the corners will chip quick.

[G59]

EZfab, Glacern has long indexable endmills. So does Shars and many others out there. You need something specific then Google is your friend.

[handlewanker]

Hi.....I bought some insert end mill cutters on EBAY, part no. BAP 300R C20-20-120-2T.

They use two APMF 1135 PDER inserts.....cutting 20mm diam and 120mm long, other lengths too.........cost A$20, shipping free......seller COSTCOCITY 003

They also sell insert end mills with one insert only designated in the part type with the 1T instead of the 2T.

The seller also has packs of 5 end mills with size range from 16mm to 25mm.... 2 inserts, same insert no, approx. A$125 free shipping......hope this helps.
Ian.

[EZfab]

G59 and wanker, thanks for the info!

[LeeWay]

I just bought a couple of Dorian insert tools on Amazon.
I do have them loaded in my tool table now, but haven't actually used them yet.
I bought a 1/2" and a dovetail. They are both very well made, which is what I have experienced from Dorian holders and inserts on the lathe.
Both are only single insert tools.
The 1/2" cutter does have a 5/8" shank, so not a good choice for a deep mill, but they do have others.
Dorian Tool E90 Indexable End Mill Holder, 1 Flute, 90 Degree, 1/2" Cutting Diameter, 3-1/4" Overall Length, 5/8" Shank Diameter: Amazon.com: Industrial & Scientific

[handlewanker]

Hi....pardon me for being ignorant.....what's the advantage if any of a single flute inset holder, or is that the only type available?.........would it be because of the small diam on the end only allowing a single inset to be mounted?

BTW....the price at $109 is a bit steep I think.
Ian.

[SCzEngrgGroup]

Hi....pardon me for being ignorant.....what's the advantage if any of a single flute inset holder, or is that the only type available?.........would it be because of the small diam on the end only allowing a single inset to be mounted?

BTW....the price at $109 is a bit steep I think.
Ian.

Yes. 1/2" insert endmills typically have room for only a single insert, though there are a few 2-insert ones out there. The $109 cost is quite reasonable, considering when you screw it up, you toss a $10-15 insert, rather than an entire $40-100 endmill. Insert endmills, where appropriate to the job, are FAR cheaper in the long run than solid carbide endmills.

Regards,
Ray L.

[LeeWay]

Ray is correct. Insert tools are much cheaper in the long run. I have bought maybe 4 1/2" carbide 4 flute end mills over the years and I hate it when they start getting dull. It means I have to order another $50 to $60 tool. These can be sharpened of course, but I haven't really found a source to sharpen them.
Insert tools just make more sense. There is a lot of meat on the end of this Dorian tool with the single insert.
Here is a 5/8" Shars for comparison. It uses two flutes. Very little meat between the to insert mounting points. The single insert will be more rigid.
Shars Tool 5/8" Cutting Diameter 2 Flute 90 Degree End Mill Cutter for APKT 1003 Insert: Amazon.com: Industrial & Scientific

Also consider that if you use the same end mill for aluminum and steel, it's design can be geared toward better cutting for one over the other type material. That will give better results for the designed material. You can get inserts the same way. Some better designed for aluminum and then others for steel, cast iron, Stainless steel etc. It takes just seconds to swap ot an insert and it doesn't really even have to come out of the spindle.

Also insert have two and three cutting sides, so they can be turned. Consider that when pricing a set of 10 inserts for a single point tool.

[handlewanker]

Hi.....in my opinion....for what it's worth....the 2 flute 20mm 2 inset end mill, I mentioned previously, does seem to have adequate metal between the flutes, provided you aren't going in to aggressively hack out large amounts of material at massive feed rates which in CNC mode is counterproductive anyway.

I haven't put them to the test yet as I'm still in the CNC learning stage....but soon no doubt.

I quite agree that being able to change tips for the material type is handy.........I paid A$38 on EBAY for 10 insets (double ended) for the above mentioned end mills........I thought A$ 0.95 per cutting edge or A$ 1.90 per end mill was quite economical.......cheaper even than HSS cutters in that diam.

BTW......I have a few 20mm diam 2 flute brazed carbide end mills with straight flutes........what is the purpose of this design as opposed to the normal solid carbide with helical flutes........they can be sharpened very easily with the most basic equipment.
Ian.

[LeeWay]

I got to use both new tools today and both are excellent. I think even better results in steel that what they replaced did when new.

Ian, the most basic sharpening equipment must be used by a skilled technician to achieve anything like sharp and concentric edges. Not quite as easy as you might think.
Those are old school low tech end mills used for quick and dirty one off jobs. Not for any kind of production work. The technology behind some of today's high end tooling is really amazing. Even some of the lower end stuff works very well even in production on standard grade materials. I started out using cheap tools on my home made mill. Man is there ever a difference a quality tool makes.

[keithmcelhinney]

I am going to be buying the 1" shear hog from tormach with the long holder. 35707 - Shear-Hog

I also will probably buy a 1" or 1.25" long endmill for finishing. Quite an expensive experiment but I will make it all up on the first part I sell.

Also have to invest in a good vise. The Shars vise I want is out of stock (of course).

-Keith

[LeeWay]

I have two of the 4" Shars double vises and priced a couple of the same style Glacerns. $800.00 each on sale. Not going there yet.

The Shars are doing the job. I made a new jaw and parallel set for them today.
Man that is a lot of jaws to make.

I did look at the shear hog, but I have a big face mill that works really well too. It is a Shars. Cannot complain at all about it. It isn't TTS is a complaint, but if it were it might be an issue too. So leave well enough alone.