rota broach cutters

[koikidder]

Hi i use rota broach cutters in my pillar drill i have used a 22mm which works great cuts perfectly but i have a 50mm which vibrates the drill and chatters i don't really get swarfs coming off it just small scrapings.

Do any of you know why? the only thing i can see different is that the adapter i have has 2 screws to clamp the cutter in and majority of my cutters have two flat surfaces but the 50mm cutter has counter sunk holes that's the only thing i can put it down to.

I am using the cutters at 160rpms and the other cutters work fine, i turned the speed up to around 400rpm and it didn't make a difference 50mm still chattered and the 22mm still cut perfectly.

Have any of you experienced this???

 

[Wendelspanswick]

What kind of pillar drill, could be that the torque is flexing the pillar if its a light weight drill.

 

[koikidder]

SIP F25-16 Floor Mounted Pillar Drill 230v (Floor Mounted)

• Sixteen Speeds Between 160-3000rpm
• Powerful 1.5hp Motor

 

[koikidder]

The adapter i bought i a mt 3 arbor which is spring loaded

 

[Wendelspanswick]

Does it cut better if you apply lots of pressure?

 

[koikidder]

I have never really forced it but when it bites into the metal it sometimes jams

 

[mike 109444]

How far are you extending the quill ? Reason more quill extended = more side movement

 

[Wendelspanswick]

Chattering is normally a sign of play, the movement sets up a vibration that bounces the cutter on the work surface.

 

[brightspark]

How far are you extending the quill ? Reason more quill extended = more side movement

= more chatter pillar drills arent substantial enough

 

[koikidder]

Im making sure that the work piece is right under the pin, the 22mm cut through 3.6mm steel like nothing is there i have just done around 150 holes and the bit is still perfect its just the 50mm cutter more scrapes than cuts, its brand new but it has a different shank on it than my other cutters im not sure if this could be knocking it out

 

[koikidder]

would i have the same problem using a standard hole saw cutter

 

[brightspark]

not if it was running slow enough. i use 3 inch ones in mine no bother

 

[Welderpaul]

It will be your drill.

We have a meaty pillar drill which we some times use broach cutters in. Anything over 50/60mm needs to be done in the big radial arm drill.

 

[roofman]

are you centre punching a dot for the pin...this greatly stops the cutter from wandering

 

[brightspark]

drills generaly only have a single thrust bearing at the bottom axial load only and not suitable for side load

 

[koikidder]

yes i use a center punch tighten everything down but it doesn't change how it cuts the smaller cutters i have 22 and 30mm cutters work perfect i didn't know if it is to do with it having a different head you can see in the photo instead of it clamping on the flat sides it clamps on the corner of the cutter

 

[roofman]

yes i use a center punch tighten everything down but it doesn't change how it cuts the smaller cutters i have 22 and 30mm cutters work perfect i didn't know if it is to do with it having a different head you can see in the photo instead of it clamping on the flat sides it clamps on the corner of the cutter

Hmmm strange that,i have a broach holder on an R8 taper for my drill and never encounted what your saying even with 52mm in it. Is your holder a magnetic type with 2 grub screws on flats??

 

[koikidder]

Yes its the full arbor in mt3 i bought of ebay from and engineering firm in Sheffield, the only thing i can see different other than the actual size of the cutter is the clamping of the cutter this cutter has countersunk holes but my adapter doesn't clamp it properly so i dont know if this could make the cutter spin in a uneven circle maybe this could of set it slightly causing it to vibrate.

all my other cutters which are flat clamping surfaces work fine

 

[koikidder]

this is it

 

[MattH]

Stop looking for other reasons. It's the size of the cutter. Chatter is a result of lack of rigidity.