# Looking for boring head and boring bars for PM-25MV mill



## devils4ever (Jan 3, 2020)

Hi all,

I'm looking for recommendations on a boring head with a set of boring bars for use with my PM-25MV mill.

I'm thinking a Shars 2" model such as: 202-8044?

As for boring bars, I've read that carbide can be an issue with smaller mills which can't provide the speed and rigidity needed compared to HSS boring bars. True?


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## macardoso (Jan 3, 2020)

I have a 2" import head on my G0704 (same size mill). Fits perfectly. Maybe not the fit and finish of an $800 boring head but it works accurately.

Carbide is fine if you prefer inserts to grinding your own tools. You can run it slow, you just won't be getting the full potential of the tool - that's fine. 90% of my tooling is indexable carbide since I prefer not to grind in my basement. Look for inserts with sharp corners (less cutting forces) and polished and ground edges for aluminum (e.g. CCGX32.50). I buy almost all of my inserts from Shars and I am happy with them.

HSS is great and usually cheaper, but requires you to grind your own tools. 

I stay away from the brazed carbide tools. Never cut well without substantial grinding effort. Not worth the effort IMO.


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## Chewy (Jan 3, 2020)

On the PM-30MV I use a 2"or 2-1/2" boring head that takes 1/2" bars. Have to look to see the brand.  The cheap carbide brazed bits work OK for me out of the box.  If I start to have a problem, I can regrind or make a HSS bit, but haven't had to.  

One thing to think about.  Mine is an integral unit.  R8 shaft and head is all one piece.  I looked special for this item.  It allows me to put the bit in backwards and run in reverse. That allows me to create a round protrusion on the item. The most common (and cheaper) boring heads are two pieces that screw to gether.  I will probaly buy a shaft and some different heads in the future but this one has done all that I wanted so far.  Just something to look into.  Lots of You Tubes on the subject including reversing the bit.   Charles


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## macardoso (Jan 3, 2020)

Good point Chewy! I opted a long time ago to go to the Tormach TTS system and used a 3/4" straight shank on my boring head. The threads were assembled with red Loctite and I've never had them come apart even when running in reverse. 

The integral straight shank is just so longggggg 

I would probably have better luck with the brazed tools if I spent more than $5-10 on the set


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## Chewy (Jan 3, 2020)

I hadn't thought about the red loctite.  Good idea!  My bars came from Wholesale Tool and at the time were about $13-14.  Nothing like top of the line quality. 

Most all of my tooling has come from Shars.  No problem with their quality.  I do buy used name brand on an auction site.  Most of my supplies are coming from KBC because of their shipping policy.


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## devils4ever (Jan 3, 2020)

Okay, so maybe I should buy the Shars 202-8024A set which comes with a 4-piece indexable Carbide boring bar set. This set should handle steel okay? 

Since I do a lot of Aluminum, I'll buy a few CCGX32.50 LH YD101 inserts? Shars number: 424-1060? I'm hoping the "LH" doesn't mean left hand, does it?


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## Chewy (Jan 3, 2020)

It appears that the LH is some form of chip breaker.  I'm thinking that the boring head came from Enco just before they closed and cost right at $100.  Have to look later.


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## macardoso (Jan 3, 2020)

That boring head looks pretty good. Truth be told I rarely ever need to swap the boring bar out of the head (I have a TCMT indexable bar, 7/16" diameter on a 1/2" shank). I don't know if you'd get a great value from having 4 bars of the same size and different lengths. I find I don't do much deep boring in my mill, and the machine itself doesn't have the travel to require a 6" bar. I find that different diameter bars are more valuable. How about considering the following:

202-8028A or 202-8044 (never seen their high precision, don't know if it is worth the extra cost)
404-7161 (Boring bar, ~7/16" diameter, 1/2" shank, TC--21 insert)
424-1659 (Spare insert for Aluminum, 3 corners)
424-1627 (Spare insert for Steel Finishing, 3 corners)
This gets you the boring head and an indexable boring bar. If you like the boring bar, then get another (either smaller or larger) to fit your work. The different sizes will probably get more use than the ones that come in that kit. Plus doing it this way is cheaper at $105.35. 

The CCGX insert I stated above is the wrong insert for the set you picked out. You'd want a TCMT21 or TCGX21, which I included in the part numbers above.

Just my thoughts,

Mike


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## raven7usa (Jan 3, 2020)

I have the Shars 202-8024A set for my PM30 mill. Only done two 1" dia. holes in 1/2" aluminum and done fine.  Kepp in mind that the division marks are .001 on the radius, or .002 for diameter on the 2" head.  I believe the 3" head it's .0005 on the radius and .001 for the diameter.


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## mikey (Jan 3, 2020)

The head most of these imported heads were cloned from is the Criterion DBL-202 boring head. This is a simple 2" boring head with three tool positions that allowed it to bore a hole from 0.050" to 6.667" ID. This head is found in almost every pro shop and a large proportion of hobby shops for a simple reason - it works, and it can work for decades if cared for. It has a direct reading leadscrew; what you dial in is what comes off the diameter, in 0.001" increments. The DBL-202 comes in two forms, the A-model that takes 3/8" shanked bars on the bottom and 1/2" bars in the horizontal tool holder and the more common B-model that takes 1/2" bars.

I have both A and B models and I much prefer to use the A-model because it uses the smaller, lighter bars. You have to remember that you are dealing with centripetal forces and mass makes a difference. 

Cost for a brand new DBL-202B head ran about $300 so a used head in good condition should run about half that or less. The A-model is less common so commands a higher price. Here is one that looks to be in decent shape, lacking only two of the three bar locking screws. The important thing to look for in a used head is that the dovetail gib is intact. It is connected to the body by a very thin remnant and can crack off if abused so look sharp when buying a used head. There should be three gib screws that touch the gib and all should be there; underneath each set screw is a ball bearing so look to see if the set screws are at the same level; if one or more is deeper then that means the ball is missing and must be replaced - I would pass on such a head.

I would take a good used Criterion head before buying a new import head but that's just me. I also have a Interstate clone of this head and its okay but you can tell the quality is lacking when compared to the real thing.

Insofar as boring bars go, you are going to find that inserted carbide bars will work for smaller diameters but the finish is going to be lacking in larger diameters. Carbide needs speed to work well and this especially applies to boring bars. Given that centripetal forces increase as speed goes up, going faster causes more vibration so that limits what a small mill can handle in terms of diameters. You will be far better off using HSS boring bars.

The best boring bars I have used are the cobalt-HSS bars from Borite. They cut well at mortal speeds, are sharpened easily, last for decades (my 3/8" set is over 25 years old and still looks and works like new) and finish far better than either brazed or inserted carbide at the speeds I use.

I think you can do well with an imported head but if it was me, I would prefer a used/new Criterion head. I would go for cobalt bars instead of carbide. LMS sells a cobalt set that looks good.


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## devils4ever (Jan 4, 2020)

mikey: Thanks for your input.

The Criterion DBL-202B head sells for $389 on MSC. I'll have to buy the shank separately, part number: R8-087520 for another $86? That's about $475. Other places might have slightly better prices. I'll have to decide if it's worth buying new or used. I'm a little leery buying used since I can't tell if it's abused, but I agree with you on buying quality. I cried once when I bought my Kurt vice, but have no regrets now.

I'll have to start scanning the auction sites for a good one at a good price.

Thanks for confirming my concerns on carbide vs HSS. That's what I remember reading awhile ago. I have no problem sharpening HSS tooling. I do this for my lathe bits. HSS boring bars, it is!


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## mikey (Jan 4, 2020)

Like your Kurt vise, I consider a boring head a foundational tool. As such, it has to work well, simply and reliably. Criterion DBL heads are actually quite basic with only a few moving parts but they are reliable workhorses that can last a hobby guy for a lifetime if not abused. Just to be clear, there are many other heads that are far better than a basic Criterion head - Wohlhaupter, Kaiser, Narex and others - but for most boring jobs, a DBL head will work just fine.

Buying a used head is economically the smartest route but you are right; buying used carries some risk. You will find that a head that has been abused or crashed will look it. If it looks like some bozo ran it into a work piece then reject it. Unscrupulous sellers will often not show the side of the head with the screws because they are invariably missing. If you can't see the screws, move on.

The body is simply black oxide coated that will fade with time and use. The tool holder part is satin chromed and stands up to wear a bit better.  If it has no battle scars, the gib is totally intact and all the screws are there then take a good look. If it was used by a good operator, the head will have many years of use left in it and you can tell these heads because they will look like someone took good care of it.

All the DBL heads had removable shanks, with a 7/8-20 internal thread in back of the head. Adapters are available for almost every conceivable application, which is one reason why this head is in widespread use. If you see a good DBL head, know that you can remove the existing shank and adapt it to your machine.

In my opinion, a head that has been used is worth about 50% of its original value. Many sellers on ebay think otherwise and I have seen heads that have been beat to death selling for nearly $300. On the other hand, there are heads that are in fine shape that sell near the $120-140 range; those are what you're looking for. Be patient and it will come. What you're looking for is the description that says in "good condition". If you buy it and there is something wrong with it, ebay will back you when you ask to return it for a full refund so there is little risk. On the other hand, if you are well-heeled and wish for a new head, wait for a set to come up on ebay that has the head and a set of boring bars in a plastic case. They will usually run less than MSC charges for the head alone.

Some examples might help.


Here is one in decent shape but you cannot see the screws. I would ask the seller to show them and the gib to me in pics. If they are all there and the gib is intact then I would make an offer. This head looks nearly new and I would offer $150 for it. He may counteroffer a bit higher but it won't be for the current asking price.
This is a DBL-202 A model in very nice condition. It is clearly used but has been well cared for. No scars, the gib is intact and the gib screws are there and equal in height so the bearings are probably in there. It is listed as used so it must be fully functional or you can return it. I would have no problem offering $110 for this head and it would probably serve me for the rest of my hobby career.
As for bars, buy a decent set. Boring bars require very little sharpening. Borite bars only need an occasional touch up on the end and a light pass on the flat top. I use an extra-fine diamond stone for this.

If you want to economize on bars, buy a solid carbide Micro 100 bar with a positive lead when you find one for a good price. You will be pleasantly surprised at how well these bars cut and one with a 1.5" - 2" long shank will bore most holes in a hobby shop. Like Borite bars, these sharpen easily with a diamond stone and will last a lifetime if you don't crash it.

Good luck. If you need help with this, PM me.


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## Aaron_W (Jan 4, 2020)

Look for used, I found a nice Criterion 1-1/2" boring head on ebay for under $100. 

The head threads onto a shank which offers some flexibility. I got it originally for my Sherline mill, but by changing the shank to an MT2 I can also use it on my Clausing mill.


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## devils4ever (Jan 4, 2020)

Thanks for the links on ebay. Most the sellers on ebay seem to be reluctant to show the screw side of the head. Maybe, for a reason. I'm asking the seller for more pics.

Interestingly, MSC sells the same head on ebay as their website for $301 with free shipping. That's a better deal than from their website. Tempting.

As for the boring bars, I'm assuming you are referencing this set on LMS: PN 2682

I recently sold my Sherline for the PM because of capacity limitations. I'm surprised the Sherline could comfortably swing the big a boring head.

This is expensive hobby for sure. I recent bought: Kurt vice, Mity 1" mic, Mity 4 piece mic set (should have started here instead of the individual one--didn't think I'd need more than 1"!), Mity 4 piece telescoping gage set, Mity depth gage set, fly cutter, many endmills plus more that I'd rather not mention! Nobody tell my wife!!!


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## Aaron_W (Jan 4, 2020)

devils4ever said:


> I recently sold my Sherline for the PM because of capacity limitations. I'm surprised the Sherline could comfortably swing the big a boring head.
> 
> This is expensive hobby for sure. I recent bought: Kurt vice, Mity 1" mic, Mity 4 piece mic set (should have started here instead of the individual one--didn't think I'd need more than 1"!), Mity 4 piece telescoping gage set, Mity depth gage set, fly cutter, many endmills plus more that I'd rather not mention! Nobody tell my wife!!!



It can be, particularly buying name brand and new stuff. That is what makes this site so nice, it is easy to get advice on where it is ok to cut a few corners buying cheap, which items are safe-ish to buy used, and where it pays to suck it up and buy a new name brand tool.

Also for suggestions of appropriate tooling for a particular machine. Mikey recommended the 1-1/2" Criterion, I also would have thought it too big and probably would have bought the Sherline boring head without his input. I think I paid the same or less for the Criterion used as I would have for new Sherline boring head.


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## mikey (Jan 4, 2020)

If the head is in really nice shape but missing the ball bearings and set screws, the price needs to reflect that. The balls can be simply replaced and the set screws are standard high quality cup point set screws so not a disaster. The gib MUST be intact, though. Yes, pics are in order before you make an offer.

MSC usually prices things lower on ebay but they kill you for shipping. I no longer buy from them because of that.

Yes, the LMS set you linked to are the ones I meant. Cheap for what they are. Borite uses M42 cobalt, or 8%, but I doubt you'll notice the difference at less than half the cost. Cobalt bars last a long time, cut clean at the speeds we use and deflect less than carbide so holding tolerances is easier. Watch for a nice Borite set on ebay, even if you get the LMS set. Criterion, Bokum and others also make cobalt bars.

As Aaron just posted, the Criterion S1-1/2 head is a perfect fit for the Sherline mill and works a treat on larger machines when you need a small hole. The advantage to the S-type heads is that they have a lot of surface area in the dovetails given their small size so they tend to be very stable in use. I have pushed that head and my Sherline mill to their limits and have been very pleased with the performance. I just gave my Sherline boring head to a friend. It isn't a POS but it ain't a Criterion, either.

I agree that this is an expensive hobby but if you know what you want and can wait for it on ebay then things are not so bad. Mitutoyo is great for digital mics and calipers. Etalon/Compac/Tesa/Interapid make the best indicators for the money. Etalon makes the best analog mics. Mitutoyo makes the best digital height gauges, and so on. Every tool we need has a "best" version and if you wait for it, you will find it on ebay at near or possibly lower cost vs their Chinese counterparts. The trick is to know what you want and look persistently. I waited for over 10 years for a set of Tesa thread mics to come up at a realistic price and I got a mint set of 0-1 and 1-2 for a relative song. It pays to buy the best but try not to pay full price for it.

Keep us posted on how things go.


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## erikmannie (Jan 5, 2020)

I wanted a boring head + R8 collet adapter and I bought the Shars 2” higher quality version (the silver one) as well as a set of Shars 1/2” brazed carbide boring bars. They look pretty nice, but I haven’t have a chance to use them yet.

I have bought a huge amount of Shars tools in the last three months. Generally speaking, I would say that they are “barely good enough”, or perhaps I should say “hopefully good enough”.

I am sure that the much higher quality brands of tools and machines are worth the extra expense, but I just cannot bring myself to spend so much extra money for a tool or machine that performs near the same as one which sells at a fraction of the price.


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## mikey (Jan 5, 2020)

I can understand your perspective, Erik. Especially when starting out, tooling expenses can get huge and you have to draw a line somewhere, right? However, allow me to offer an optional perspective.

There are tools that I consider to be foundational tools, tools that impact on accuracy. These tools include a good machine vise, boring head and bars, collet chuck/collets/collet nut for the mill and jawed lathe chucks. This is where quality pays off and is where going cheap will affect accuracy. 

This doesn't mean paying retail. Ebay allows us to afford the finest tools for a fraction of their retail value. Many of my best tools were cheaper than their new Chinese equivalents. My personal practice is to know what I want, wait for it to turn up on ebay and get that instead of opting for a cheaper alternative.


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## darkzero (Jan 6, 2020)

Aside from buying a used Criterion on ebay, which would also be my first choice over a Chinese import, and is how I got my DBL-202, look for Yuasa on ebay. Yuasa also copied the Criterion DBL boring heads but Yuasa makes quality tools. Many people don't think to search for Yuasa boring heads & they don't pop up that often but if you have the patience & keep your eyes open you may find one for a really good deal. 

I scored a Yuasa 3" boring head for really cheap, made in Japan. Unfortunately I never use it as I don't have a need for a 3" head but I have it if I ever need it. Was one of those throw a low bid & forget about it deals. I won the auction with no other bidders.



devils4ever said:


> The Criterion DBL-202B head sells for $389 on MSC.





devils4ever said:


> Interestingly, MSC sells the same head on ebay as their website for $301 with free shipping. That's a better deal than from their website. Tempting.



If you log into to your account on MSC the price should be cheaper. Yeah it sucks that their pricing works that way but they are not the only ones that do that. Plus on their website you can apply codes for sales when they have them for additional discount if the certain item allows for further discount (depends on their profit margin for certains). And shipping is free for orders over $49. However I haven't figured out if it's the same for all low volume buyers' accounts so YMMV.


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## devils4ever (Jan 6, 2020)

Does anyone know the deal with the model numbers for these heads?

I see models DBL-202B and CB-202B. Are they the same? Did CB-202B replace DBL-202B? I get the feeling that the CB-202B model is the newer version of the DBL-202B, but I can't tell for sure.


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## devils4ever (Jan 6, 2020)

Okay, I scored the Criterion DBL-202B on eBay, but it needs the set screws and ball bearings. Does anyone know where I can get these? Allied directly Or, MSC?


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## pontiac428 (Jan 6, 2020)

@devils4ever you will be glad you went that route (used Criterion vs new Chinerion), and I will go out on a limb and say you will realize probably sooner than later that you dodged a bullet.  I bought two different china boring heads, two-piece type with the threaded arbor.  I could not get good results with them, and started to wonder if I was any good at shop work.  Turns out the fit and finish matter a whole bunch on a boring head.  It needs to adjust predictably, tighten up without moving, and NOT wobble when the arbors were threaded in!  I bought a Yuasa Japan on the bay and now I can bore good holes... and will be doing so for a lifetime, Allah willing.


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## darkzero (Jan 6, 2020)

devils4ever said:


> Does anyone know the deal with the model numbers for these heads?
> 
> I see models DBL-202B and CB-202B. Are they the same? Did CB-202B replace DBL-202B? I get the feeling that the CB-202B model is the newer version of the DBL-202B, but I can't tell for sure.



CBs are their newest models. DBLs are no longer made by Criterion. I have no idea what the differences are, never looked into it.



devils4ever said:


> Okay, I scored the Criterion DBL-202B on eBay, but it needs the set screws and ball bearings. Does anyone know where I can get these? Allied directly Or, MSC?



You don't need to buy genuine replacement parts for these. They should just be standard size set screws. You can get replacements from Mcmaster (will be in bulk quanities though) or your local hardware store. Ball bearing quality/hardness may vary from your local hardware store though.


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## devils4ever (Jan 19, 2020)

Here's an update.

I bought the used ebay boring head mentioned above, but the seller was a little deceitful. One of the gib screw holes was messed up and unusable. The ball bearing was jammed in there and the threads were messed up. I sent it back and I'm waiting for a refund. Ebay picked up return shipping. See pics below.

So, I decided to buy new. I got the boring head from MSC via ebay for $300 and I bought a R8 shank from MSC's regular website.


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## springer (Jan 27, 2020)

Wish I would have seen this earlier. I have 2 criterion boring heads that I’ve never used


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## devils4ever (Jan 28, 2020)

Now, you tell me!!!!


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## devils4ever (Jan 28, 2020)

I used this boring head over the weekend. 

I noticed a little "reluctance" for the R8 shank to go all the way into the spindle. The last 1/4" or so was not cooperating. It required gentle persuasion. I even removed the alignment screw in the spindle, but it didn't help. 

I have other R8 arbor tooling that doesn't have this problem. It this shank built to tighter tolerances? I didn't see any marks on the shank indicating where it was hanging up.


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